Heat exchanger

ABSTRACT

In a composite-type heat exchanger capable of exchanging heat among three types of fluids, an outside air passage is provided in a periphery of refrigerant tubes and coolant tubes, and the outside air passage includes outer fins that promote heat exchange among a refrigerant, an outside air and a coolant. The outer fins include refrigerant side heat connecting portions configured to thermally connect the refrigerant tubes, and coolant side heat connecting portions configured to thermally connect the refrigerant tubes and the coolant tubes. In a first core portion including most downstream refrigerant tubes which constitute a final path, which is the most downstream side path in a direction of the refrigerant flow, the refrigerant side heat connecting portions is larger in number than the coolant side heat connecting portions.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by referenceJapanese Patent Application No. 2012-249441 filed on Nov. 13, 2012.

TECHNICAL FIELD

The present disclosure relates to a composite-type heat exchangerconfigured to be capable of performing heat exchanges among three kindsof fluids.

BACKGROUND ART

Conventionally, a composite-type heat exchanger configured to be capableof performing heat exchanges among three types of fluids is known. Forexample, disclosed in Patent Document 1 is a composite-type heatexchanger including a refrigerant radiator that performs heat exchangebetween a refrigerant (a first fluid) discharged from a compressor in arefrigeration cycle and a blown air (a third fluid) such that a heat ofthe discharged refrigerant is radiated to the blown air, and a radiatorthat performs heat exchange between a coolant (a second fluid) forcooling an engine and a blown air to radiate heat of the coolant to theblown air combined into one unit as a single heat exchanger.

Specifically, disclosed in Patent Document 1 is a heat exchangerincluding refrigerant tubes in which the discharged refrigerant flows,coolant tubes in which the coolant flows arranged in a stacked manner,and outer fins arranged in outside air passages configured to allow theoutside air to flow therein. Each outer fin is formed between therefrigerant tube and the coolant tube adjacent to each other andconfigured to allow heat transfer between the refrigerant tubes and thecoolant tubes. Accordingly, not only the heat exchange between therefrigerant and the blown air and the heat exchange between the coolantand the blown air, but also the heat exchange between the refrigerantand the coolant are achieved.

PRIOR ART DOCUMENT Patent Document

Patent Document 1: JP 2012-144245 A

SUMMARY OF THE INVENTION

In the refrigeration cycle, normally, a degree of subcooling of therefrigerant flowing out from the refrigerant radiator is controlled toachieve a maximum coefficient of performance (COP) of the cycle.

According to a study of the inventors of the present application, withthe composite-type heat exchanger described in Patent Document 1, in asubcooling portion configured to subcool the condensed refrigerant inthe refrigerant radiator, regions of the outer fins arranged between therefrigerant tubes that form the subcooling portion and the coolant tubesadjacent to the refrigerant tubes, which are used for discharging theheat of the coolant to the outside air are excessively increased, andregions thereof used for discharging the heat of the dischargedrefrigerant to the outside air become small. Therefore, in order toprovide the refrigerant on the outlet side of the refrigerant radiatorwith a desired degree of subcooling, the length of the refrigerant tubesthat forms the subcooling portion needs to increase to increase thetotal surface area of the outer fins connected to the coolant tubes.

However, the subcooling portion in the refrigerant radiator has anextremely low heat transmitting rate on tube wall surfaces in comparisonwith a condenser (the heat radiating portion in the refrigerant radiatorother than the subcooling portion). In contrast, the refrigerant tubesthat form the condenser have a high heat transmitting rate on the tubewall surfaces, and have a high heat exchanging performance. Therefore,when the length of the tubes that form the subcooling portion isincreased, the length of the refrigerant tubes that form the condenseris reduced, so that the heat exchanging performance of the refrigerantradiator as a whole may be deteriorated.

In view of such points described above, it is an objective of thepresent disclosure to limit reduction in heat exchanging capacity of acomposite-type heat exchanger as a whole while the heat exchanger isconfigured to be capable of performing heat exchanges among three typesof fluids.

According to an aspect of the present disclosure, a heat exchangerincludes a plurality of first tubes in which a first fluid flows, aplurality of second tubes in which a second fluid flows, a heat exchangeportion including the plurality of first tubes and the plurality ofsecond tubes arranged in a stacked manner and configured to radiateheats of the first fluid and the second fluid to a third fluid, a thirdfluid channel in which the third fluid flows, the third fluid channelbeing provided in a periphery of the plurality of first tubes and theplurality of second tubes, and an outer fin arranged in the third fluidchannel to promote a heat exchange between the first fluid and the thirdfluid and a heat exchange between the second fluid and the third fluid.The outer fin includes a first heat connecting portion thermallyconnecting the plurality of first tubes, and a second heat connectingportion thermally connecting the plurality of first tubes and theplurality of the second tubes. The plurality of first tubes is dividedinto a plurality of groups, and the plurality of groups of the pluralityof first tube are paths through which the first fluids distributed froma same space flow in a same direction. The plurality of first tubesinclude most downstream first tubes which constitute a part of a finalpath that is a most downstream path in a flowing direction of the firstfluid. The heat exchange portion includes a first core portion includingthe most downstream first tubes. The first heat connecting portions arelarger in number than the second heat connecting portions in the firstcore portion.

In this configuration, in a heat exchange portion including the mostdownstream first tubes, since the number of the first heat connectingportions is set to be larger than the number of the second heatconnecting portions, an area used for radiating heat of the first fluidto the third fluid is larger than an area used for radiating heat of thesecond fluid to the third fluid in the outer fins arranged in the heatexchanger including the most downstream first tubes. Therefore, the heatof the first fluid flowing in the most downstream first tubes may beradiated sufficiently to the third fluid.

Therefore, lengths of the most downstream first tubes does not have tobe increased in order to achieve a desired temperature as thetemperature of the first fluid on the outlet side of the heat exchanger,that is, lengths of first tubes which do not form the final path doesnot have to be decreased, and hence reduction of the heat exchangingperformance as the entire heat exchanger may be limited.

The expression “arrange the first tubes and the second tubes in astacked manner” means that the first tubes and the second tubes arearranged in a stacked manner in a given order, and does not limit theorder of arrangement of the first tubes and the second tubes. Theexpression “the number of the first heat connecting portions is largerthan the number of the second heat connecting portions” includes a casewhere the number of the second heat connecting portions is zero.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a vehicle air conditioning system of afirst embodiment of the present disclosure.

FIG. 2 is a perspective view of a composite-type heat exchanger of thefirst embodiment.

FIG. 3 is an exploded perspective view of the composite-type heatexchanger of the first embodiment.

FIG. 4 is a cross-sectional view taken along a line IV-IV of FIG. 2.

FIG. 5 is a cross-sectional view taken along a line V-V of FIG. 2.

FIG. 6 is a schematic perspective view for explaining a refrigerant flowand a coolant flow in the composite-type heat exchanger of the firstembodiment.

FIG. 7 is a characteristic diagram illustrating a relationship between adegree of subcooling and a heat-radiating capacity of a refrigerant.

FIG. 8 is a schematic cross-sectional view taken in a longitudinaldirection of a heat exchange portion and illustrating a first coreportion of a composite-type heat exchanger according to a secondembodiment of the present disclosure.

FIG. 9 is a schematic perspective view for explaining a refrigerant flowand a coolant flow in a composite-type heat exchanger of a thirdembodiment of the present disclosure.

FIG. 10 is a schematic perspective view for explaining a refrigerantflow and a coolant flow in a composite-type heat exchanger of a fourthembodiment of the present disclosure.

FIG. 11 is a schematic diagram illustrating a heat pump cycle and a flowchannel of the coolant circuit at the time of a heating operation of afifth embodiment of the present disclosure.

FIG. 12 is a schematic diagram illustrating a heat pump cycle and a flowchannel of the coolant circuit at the time of a defrosting operation ofthe fifth embodiment.

FIG. 13 is a schematic diagram illustrating the heat pump cycle and theflow channel of the coolant circuit at the time of a cooling operationof the fifth embodiment.

FIG. 14 is a schematic diagram illustrating a heat pump cycle and a flowchannel of the coolant circuit at the time of a heating operation of asixth embodiment of the present disclosure.

FIG. 15 is a schematic diagram illustrating the heat pump cycle and theflow channel of the coolant circuit at the time of warm-up operation ofthe sixth embodiment.

FIG. 16 is a schematic diagram illustrating the heat pump cycle and theflow channel of the coolant circuit at the time of a cooling operationof the sixth embodiment.

FIG. 17 is a schematic perspective view for explaining a refrigerantflow and a coolant flow in a composite-type heat exchanger of amodification of the present disclosure.

EMBODIMENTS FOR EXPLOITATION OF THE INVENTION

Hereinafter, multiple embodiments for implementing the present inventionwill be described referring to drawings. In the respective embodiments,a part that corresponds to a matter described in a preceding embodimentmay be assigned the same reference numeral, and redundant explanationfor the part may be omitted. When only a part of a configuration isdescribed in an embodiment, another preceding embodiment may be appliedto the other parts of the configuration. The parts may be combined evenif it is not explicitly described that the parts can be combined. Theembodiments may be partially combined even if it is not explicitlydescribed that the embodiments can be combined, provided there is noharm in the combination.

First Embodiment

A first embodiment of the present disclosure will be described withreference to FIG. 1 to FIG. 7. In the present embodiment, a heatexchange system of the present disclosure is applied to a vehicle airconditioning apparatus 1 for so-called a hybrid vehicle that obtains adrive force for traveling a vehicle from an internal combustion engine(an engine) and a traveling electric motor MG.

The hybrid vehicle is capable of being switched between a travelingstate in which the engine is activated or stopped depending on atraveling load of the vehicle and a drive force is obtained both fromthe engine and the traveling electric motor MG to travel and a travelingstate in which the engine is stopped and the drive force is obtainedonly from the traveling electric motor MG to travel. Accordingly, in thehybrid vehicle, a vehicle fuel efficiency for normal vehicles whichobtain the drive force for traveling the vehicle only from the enginecan be improved.

The heat exchange system applied to the vehicle air conditioningapparatus 1 of the present embodiment includes a heat pump cycle 10,which is a vapor compression refrigeration cycle, a coolant circulationcircuit 40 in which a coolant configured to cool the traveling electricmotor MG circulates, and the like.

First of all, the heat pump cycle 10 performs a function of cooling ablown air to be blown into a vehicle interior which is a space to beair-conditioned in the vehicle air conditioning apparatus 1. The heatpump cycle 10 employs a normal fluorocarbon refrigerant as therefrigerant, and constitutes a part of a subcritical refrigeration cyclein which a high pressure side refrigerant pressure does not exceed acritical pressure of the refrigerant. Refrigerant oil for lubricating acompressor 11 is mixed with the refrigerant, and a portion of therefrigerant oil circulates in the cycle together with the refrigerant.

The compressor 11 is an electric compressor arranged in an engine roomand sucks, compresses, and discharges the refrigerant in the heat pumpcycle 10, is configured to drive a fixed capacity type compressor 11 awith a fixed discharge capacity by an electric motor 11 b. Specifically,various compression mechanisms such as a scroll-type compressionmechanism and a vane-type compression mechanism can be employed as thefixed capacity type compressor 11 a.

The operation (a number of rotations) of the electric motor 11 b iscontrolled by a control signal that is output from a control apparatus,which will be described later, and any one of an AC motor and a DC motormay be employed as the electric motor 11 b. The refrigerant dischargingcapacity of the compressor 11 changes according to thenumber-of-rotations control. Therefore, in the present embodiment, theelectric motor 11 b constitutes a part of discharge capacity changemeans of the compressor 11.

A refrigerant inlet side of a refrigerant radiator 12 is connected to arefrigerant discharge port of the compressor 11. The refrigerantradiator 12 is a radiation heat exchanger arranged in the engine room,and configured to cause a discharged refrigerant (a first fluid)discharged from the compressor and outside air as a fluid to be heatexchanged (a third fluid) blown from a blower fan 13 to exchange heatwith each other and discharge the heat of the discharged refrigerant tothe outside air.

The blower fan 13 is an electric blower of which an operation rate, thatis, a number of rotations (an amount of blown air) is controlled by acontrol voltage output from the control apparatus. The refrigerantradiator 12 of the present embodiment is combined integrally with aradiator (a heat medium radiator) 43 described later configured to causea coolant (a second fluid) as heat medium for cooling the travelingelectric motor MG and the outside air blown from the blower fan 13 toexchange heat with each other.

Therefore, the blower fan 13 of the present embodiment constitutes apart of exterior blowing means configured to blow outside air towardboth the refrigerant radiator 12 and the radiator 43. Detailedconfiguration of the integrated refrigerant radiator 12 and the radiator43 (hereinafter, referred to as a composite-type heat exchanger 70) willbe described later.

A receiver 14 configured to separate gas and liquid of the refrigerantflowing out from the refrigerant radiator 12 and accumulate an excessiveliquid-phase refrigerant is arranged on a refrigerant outlet side of therefrigerant radiator 12. In addition, an inlet side of a temperaturetype expansion valve 15 is connected to an outlet of the liquid-phaserefrigerant of the receiver 14, and a refrigerant inlet side of arefrigerant evaporator 16 is connected to an outlet side of thetemperature type expansion valve 15.

The temperature type expansion valve 15 is decompression means includinga temperature sensing unit, which is not illustrated, arranged in arefrigerant passage on the outlet side of the refrigerant evaporator 16,configured to detect a degree of superheat of the refrigerant on theoutlet side of the refrigerant evaporator 16 on the basis of atemperature and a pressure of the refrigerant on the outlet side of therefrigerant evaporator 16, and adjust a valve opening (refrigerant flowrate) by a mechanic mechanism so that the degree of superheat of therefrigerant on the outlet side of the refrigerant evaporator 16 fallswithin a value of a predetermined range set in advance.

The refrigerant evaporator 16 is a cooling heat exchanger arranged in acasing 31 of an indoor air conditioning unit 30, configured to cause alow-pressure refrigerant decompressed and expanded by the temperaturetype expansion valve 15 and the blown air blown into the vehicleinterior to exchange heat with each other, and cool the blown air byevaporating the low-pressure refrigerant. A refrigerant inlet port ofthe compressor 11 is connected to the refrigerant outlet side of therefrigerant evaporator 16.

Next, the indoor air conditioning unit 30 will be described. The indoorair conditioning unit 30 is arranged inside of a dashboard panel (aninstrument panel) in a foremost portion of the vehicle interior, andincludes a blower 32, the above described refrigerant evaporator 16, theelectric heater 36, and the like accommodated in the casing 31 whichforms an outer shell thereof.

The casing 31 forms an air passage for a blown air that is blown intothe vehicle interior in the interior thereof, and is made of a resin(for example, polypropylene) that has a certain degree of elasticity andis also excellent in terms of strength. An inside and outside airswitching unit 33 configured to switch introduce air between the vehicleinterior (inside air) and the outside air is arranged on the mostupstream side of the blown airflow in the interior of the casing 31.

The inside and outside air switching unit 33 is provided with inside airinlet port for guiding the inside air into the interior of the casing 31and the outside air inlet port for guiding the outside air therein.Furthermore, the inside and outside air switching unit 33 includes aninside and outside air switching door configured to adjust opening areasof the inside air inlet port and the outside air inlet port continuouslyto change an air volume ratio between an air volume of the inside airand an air volume of the outside air arranged in the interior thereof.

The blower 32 that blows the air sucked through the inside and outsideair switching unit 33 toward the vehicle interior is arranged on thedownstream side of the inside and outside air switching unit 33 in thedirection of the airflow. The blower 32 is an electrical blower thatdrives a centrifugal multiblade fan (a sirocco fan) with an electricmotor, and the number of rotations (a blowing rate) thereof iscontrolled by a control voltage that is output from the controlapparatus.

The refrigerant evaporator 16 and the electric heater 36 are arranged onthe downstream side of the blower 32 in the direction of the airflow inthis order with respect to the flow of the blown air. In other words,the refrigerant evaporator 16 is arranged on the upstream side in theflowing direction of the blown air with respect to the electric heater36. The electric heater 36 is heating means including a PTC element(positive characteristic thermistor), configured to generate heat by thecontrol apparatus supplying electric power to the PTC element, andheating air after a passage through the refrigerant evaporator 16.

In addition, an air mixture door 34 configured to adjust an air volumeproportion of the air that passes through the electric heater 36 to theblown air that has passed through the refrigerant evaporator 16 isarranged on the downstream side of the refrigerant evaporator 16 in thedirection of airflow, and on the upstream side of the electric heater 36in the direction of the airflow. In addition, a mixing space 35 thatmixes the blown air heated by the electric heater 36 by the heatexchange with the refrigerant and the blown air which is not heated bybypassing the electric heater 36 is provided on the downstream side ofthe electric heater 36 in the direction of the airflow.

Outlet port for blowing out an air conditioning wind mixed in the mixingspace 35 into the vehicle interior, which is a space to be cooled, isarranged on the most downstream portion of the casing 31 in thedirection of the airflow. Specifically, a face outlet port through whichthe air conditioning wind is blown out toward an upper body of anoccupant present in the vehicle interior, a foot outlet port throughwhich the air conditioning wind is blown out toward feet of an occupant,and a defroster outlet port through which the air conditioning wind isblown out toward an inner surface of a windshield of a vehicle (none ofwhich is illustrated) are provided as this outlet port.

Therefore, the air mix door 34 adjusts the proportion of the air volumethat passes through the electric heater 36 to adjust a temperature ofthe air conditioning wind mixed in the mixing space 35, and adjust thetemperature of the air conditioning wind blown out from the respectiveoutlet ports. In other words, the air mix door 34 constitutes a part oftemperature adjusting means configured to adjust the temperature of theair conditioning wind that is blown into the vehicle interior. The airmix door 34 is driven by a servo motor, which is not illustrated,controlled in operation by the control signal output from the controlapparatus.

Furthermore, face doors for adjusting the opening areas of the faceoutlet ports, foot doors for adjusting the opening areas of the footoutlet ports, and defroster doors for adjusting the opening areas of thedefroster outlet ports (none of which are illustrated) are arranged onthe upstream sides of the face outlet ports, the foot outlet ports, andthe defroster outlet ports in the direction of the airflow,respectively.

The face door, the foot door, and the defroster door constitute a partof outlet port mode switching means configured to switch an outlet portmode, and are driven by the servo motor, which is not illustrated,controlled in operation by the control signal output from the controlapparatus via a link mechanism or the like.

Subsequently, the coolant circulation circuit 40 will be described. Thecoolant circulation circuit 40 is a heat medium circulation circuitconfigured to flow the coolant (for example, ethylene glycol aqueoussolution) as a heat medium in a coolant flow channel formed in theinterior of the traveling electric motor MG, which is a vehicle-mounteddevices associated with heat generation at the time of operation, tocool the traveling electric motor MG. The coolant circulation circuit 40includes a coolant pump 41 and the radiator 43 arranged therein.

The coolant pump 41 is an electric water pump configured to pump thecoolant into the coolant flow channel formed in the interior of thetraveling electric motor MG in the coolant circulation circuit 40, andis controlled in number of rotations (flow rate) by the control signaloutput from the control apparatus.

When the control apparatus activates the coolant pump 41, the coolantcirculates from the coolant pump 41 the traveling electric motor MG→theradiator 43→the coolant pump 41 in this order. Therefore, the coolantpump 41 constitutes a part of heat medium flow rate adjusting means(second fluid flow rate adjusting means) configured to adjust the inflowrate of the coolant flowing into the radiator 43.

The radiator 43 is a radiation heat exchanger arranged in an engineroom, and configured to causes a coolant (the second fluid) flowing outfrom the coolant flow channel formed in the interior of the travelingelectric motor MG and the outside air (the third fluid) blown from theblower fan 13 to exchange heat with each other to radiate heat of thecoolant to the outside air.

Therefore, in the coolant circulation circuit 40, when the controlapparatus activates the coolant pump 41, the coolant absorbs waste heatof the traveling electric motor MG when the coolant passes through thetraveling electric motor MG thereby cooling the traveling electric motorMG. In addition, the coolant increased in temperature by absorbing thewaste heat of the traveling electric motor MG flows into the radiator43, radiates heat to the outside air, and is cooled. In other words, thetraveling electric motor MG plays a function as an external heat sourceconfigured to heat the coolant.

Subsequently, with reference to FIG. 2 to FIG. 6, a detailedconfiguration of the composite-type heat exchanger 70 will be described.First of all, the composite-type heat exchanger 70 is a composite-typeheat exchanger including the refrigerant radiator 12 and the radiator 43combined into one unit as a single heat exchanger. The refrigerantradiator 12 and the radiator 43 are configured as so-called atank-and-tube-type heat exchanger having a plurality of tubes 12 a, 43 aconfigured to flow the refrigerant or the coolant, respectively, and apair of collection and distribution tanks 12 b, 43 b arranged on bothend sides of the plurality of tubes and configured to collect ordistribute the refrigerant or the coolant flowing in the respectivetubes.

The composite-type heat exchanger 70 includes the refrigerant tubes 12 aconfigured to allow the refrigerant as the first fluid to flow thereinand the coolant tubes 43 a configured to allow the coolant as the secondfluid to flow therein in the interior thereof.

Here, the plurality of refrigerant tubes 12 a are divided into aplurality of groups, and the plurality of groups of the refrigeranttubes 12 a correspond to paths configured to flow the refrigerantdistributed from the same space in the same direction, respectively. Therefrigerant tubes 12 a include a most downstream refrigerant tubes 121 a(most downstream first tubes) that form final paths, which are paths ona most downstream side in the refrigerant flow direction.

The composite-type heat exchanger 70 includes a first core portion 701formed only by the most downstream refrigerant tubes 121 a and a secondcore portion 702 formed by both of the refrigerant tubes 12 a and thecoolant tubes 43 a. In other words, in the composite-type heat exchanger70, the first core portion 701, which corresponds to a heat exchangeportion formed only by the most downstream refrigerant tubes 121 a isprovided independently from the second core portion 702, which is theother heat exchange portion.

In the present embodiment, the second core portion 702 constitutes apart of a condenser configured to radiate the heat from a high-pressurerefrigerant flowing in the refrigerant tubes 12 a and condense thehigh-pressure refrigerant, and the first core portion 701 constitutes apart of a subcooling portion configured to subcool the liquid phaserefrigerant flowed out from the second core portion 702 (condenser).

More specifically, the composite-type heat exchanger 70 is provided withan upstream heat exchanging portion 71 formed by arranging therefrigerant tubes 12 a and the coolant tubes 43 a in an stacked manner.The upstream heat exchanging portion 71 is a heat exchange portionconfigured to cause the refrigerant flowing in the refrigerant tubes 12a and the air as the third fluid flowing around the refrigerant tubes 12a (the outside air blown from the blower fan 13) to exchange heat witheach other and the coolant flowing in the coolant tubes 43 a and the airflowing around the coolant tubes 43 a (the outside air blown from theblower fan 13) to exchange heat with each other.

A portion of the upstream heat exchanging portion 71 which constitutes apart of the first core portion 701 includes only the most downstreamrefrigerant tubes 121 a arranged in a stacked manner. In contrast, aportion of the upstream heat exchanging portion 71 which constitutes thesecond core portion 702 includes the refrigerant tubes 12 a and thecoolant tubes 43 a arranged in an alternately stacked manner.

A downstream heat exchanging portion 72 including the refrigerant tubes12 a arranged in a stacked manner is provided on the downstream side ofthe upstream heat exchanging portion 71 in the direction of the flow ofthe outside air. In other words, the downstream heat exchanging portion72 includes only the refrigerant tubes 12 a. The downstream heatexchanging portion 72 is the heat exchange portion configured to causethe refrigerant flowing in the refrigerant tubes 12 a and the airflowing around the refrigerant tubes 12 a (the outside air blown fromthe blower fan 13) to exchange heat with each other.

As the refrigerant tubes 12 a and the coolant tubes 43 a, flat tubeshaving a flat shape in a vertical cross section in the longitudinaldirection are employed. More specifically, as the refrigerant tubes 12a, tubes having a flat porous cross section molded by an extrusionprocessing are employed. As the coolant tubes 43 a, tubes having a flatcross section having two holes formed by bending a single plate materialare employed.

The refrigerant tubes 12 a and the coolant tubes 43 a which constitute apart of the second core portion 702 of the upstream heat exchangingportion 71 are arranged at a predetermined distance in an alternatelystacked manner with a flat surfaces thereof out of an outer surfaces inparallel to each other and so as to oppose each other. In the samemanner, the most downstream refrigerant tubes 121 a which constitute apart of the first core portion 701 of the upstream heat exchangingportion 71 and the refrigerant tubes 12 a which constitute a part of thedownstream heat exchanging portion 72 are arranged at a predetermineddistance in a stacked manner, respectively.

The refrigerant tubes 12 a which constitute a part of the second coreportion 702 of the upstream heat exchanging portion 71 are arrangedbetween the coolant tubes 43 a, and the coolant tubes 43 a are arrangedbetween the refrigerant tubes 12 a. The refrigerant tubes 12 a whichconstitute a part of the downstream heat exchanging portion 72 and therefrigerant tubes 12 a or the coolant tubes 43 a which constitute a partof the upstream heat exchanging portion 71 are arranged so as to overlapwith each other when viewing from a flowing direction of an outside airblown by the blower fan 13.

In the heat exchanger 70, a space formed between the refrigerant tubes12 a and the coolant tubes 43 a which constitute a part of the upstreamheat exchanging portion 71 and a space formed between the adjacentrefrigerant tubes 12 a which constitute a part of the downstream heatexchanging portion 72 form an outside air passage 70 a (a third fluidchannel) in which the outside air blown by the blower fan 13 flows.

In the outside air passage 70 a, outer fins 70 b configured to promotethe heat exchange between the refrigerant and the outside air and theheat exchange between the coolant and the outside air, and allows heattransfer between the refrigerant flowing in the refrigerant tubes 12 awhich constitute a part of the upstream heat exchanging portion 71 andthe coolant flowing in the coolant tubes 43 a and heat transfer of therefrigerants flowing in the adjacent refrigerant tubes 12 a whichconstitute a part of the downstream heat exchanging portion 72 arearranged.

As the outer fins 70 b, corrugate fins formed by bending a metallic thinplate having superior heat transfer properties into a wave shape areemployed and, in the present embodiment, the outer fins 70 b are joinedto both of the refrigerant tubes 12 a and the coolant tubes 43 a whichconstitute a part of the upstream heat exchanging portion 71, so thatthe heat transfer between the refrigerant tubes 12 a and the coolanttubes 43 a is enabled. Furthermore, the outer fins 70 b are joined tothe adjacent refrigerant tubes 12 a which constitute a part of thedownstream heat exchanging portion 72, so that the heat transfer betweenthe adjacent refrigerant tubes 12 a is enabled.

The outer fins 70 b include refrigerant side heat connecting portions(first heat connecting portions) 71 b configured to thermally connectthe refrigerant tubes 12 a, and coolant side heat connecting portions(second heat connecting portions) 72 b configured to thermally connectthe refrigerant tubes 12 a and the coolant tubes 43 a. Specifically, theouter fins 70 b arranged between the refrigerant tubes 12 a include therefrigerant side heat connecting portions 71 b. In contrast, the outerfins 70 b arranged between the refrigerant tubes 12 a and the coolanttubes 43 a include both of the refrigerant side heat connecting portions71 b and the coolant side heat connecting portions 72 b.

As described above, the first core portion 701 of the present embodimentincludes only the most downstream refrigerant tubes 121 a. Therefore, inthe first core portion 701, the number of the coolant side heatconnecting portions 72 b becomes zero. Therefore, in the first coreportion 701, the number of the refrigerant side heat connecting portions71 b is larger than the number of the coolant side heat connectingportions 72 b.

Dummy tubes 77 in which neither the refrigerant nor the coolant flowsare arranged between the most downstream refrigerant tubes 121 a whichform the first core portion 701 and the coolant tubes 43 a which formthe second core portion 702. The dummy tubes 77 may have a hollowcylindrical shape, or may have a solid (that is, not hollow) columnshape.

Subsequently, upstream side tank units 73 and downstream side tank units74 will be described. The composite-type heat exchanger 70 includes theupstream side tank units 73 extending in the stacking direction of therefrigerant tubes 12 a and the coolant tubes 43 a which constitute apart of the upstream heat exchanging portion 71, and the downstream sidetank units 74 extending in the stacking direction of the refrigeranttubes 12 a which constitute a part of the downstream heat exchangingportion 72.

Each of the upstream side tank units 73 is provided with an upstreamside coolant space 731 configured to perform collection or distributionof the coolant flowing in the coolant tubes 43 a which constitute a partof the upstream heat exchanging portion 71 formed therein. Each of thedownstream side tank units 74 is provided with a downstream siderefrigerant space 741 configured to perform collection or distributionof the refrigerant tubes 12 a which constitute a part of the downstreamheat exchanging portion 72 formed therein.

The upstream side tank unit 73 and the downstream side tank unit 74 areformed integrally. Hereinafter, a configuration in which the upstreamside tank unit 73 and the downstream side tank unit 74 are combined intoone unit is referred to as a header tank 75.

The header tank 75 includes a header plate 751 to which the refrigeranttubes 12 a and the coolant tubes 43 a arranged in two rows in flowingdirection of the outside air are both fixed, an intermediate platemember 752 fixed to the header plate 751, and a tank forming member 753.

The tank forming member 753 is fixed to the header plate 751 and theintermediate plate member 752 whereby the upstream side coolant space731 and the downstream side refrigerant space 741 described above areformed in an interior thereof. Specifically, the tank forming member 753is formed into a double-mountain shape (a W-shape) when viewing from thelongitudinal direction thereof by applying press process on a flat metalplate.

A double-mountain shaped center portion 753 c of the tank forming member753 is joined to the intermediate plate member 752, whereby the upstreamside coolant space 731 and the downstream side refrigerant space 741 arepartitioned.

The intermediate plate member 752 is provided with a plurality ofdepressed portions 752 a that form a plurality of communicating spaces76 communicating with the coolant tubes 43 a formed between theintermediate plate member 752 and the header plate 751 by being fixed tothe header plate 751 as illustrated in cross-sectional views in FIG. 4and FIG. 5.

On the downstream side of the outside airflow in the depressed portions752 a, in other words, in a portion corresponding to the downstream siderefrigerant space 741 of each of the downstream side tank units 74,first through holes 752 b penetrating therethrough from the front to theback thereof are formed. Accordingly the communicating spaces 76 and thedownstream side refrigerant space 741 of each of the downstream sidetank units 74 communicate with each other.

Therefore, the refrigerant flowed from the refrigerant tubes 12 a whichconstitute a part of the upstream heat exchanging portion 71 into thecommunicating spaces 76 flows out from the first through hole 752 b tothe downstream side refrigerant space 741. Therefore, the communicatingspaces 76 have a function as communication paths configured tocommunicate the refrigerant tubes 12 a which constitute a part of theupstream heat exchanging portion 71 and the downstream side refrigerantspace 741 of the downstream side tank units 74.

The communicating spaces 76 extend in a direction connecting ends of therefrigerant tubes 12 a arranged so as to overlap with each other whenviewing in the flowing direction of the outside air out of therefrigerant tubes 12 a which constitute a part of the upstream heatexchanging portion 71 and the refrigerant tubes 12 a which constitute apart of the downstream heat exchanging portion 72.

More specifically, the communicating spaces 76 extend at the ends of therefrigerant tubes 12 a which constitute a part of the upstream heatexchanging portion 71 and of the refrigerant tubes 12 a which constitutea part of the downstream heat exchanging portion 72 in the flowingdirection of the outside air.

At portions corresponding to the coolant tubes 43 a which constitute apart of the upstream heat exchanging portion 71 in the intermediateplate member 752, second through holes 752 c penetrating therethroughfrom the front to the back thereof are formed. The coolant tubes 43 awhich constitute a part of the upstream heat exchanging portion 71penetrate through the second through holes 752 c. Accordingly, thecoolant tubes 43 a which constitute a part of the upstream heatexchanging portion 71 communicate with the upstream side coolant space731 formed in the tank forming member 753.

Furthermore, as illustrated in FIG. 3, at ends of the upstream heatexchanging portion 71 on the header tanks 75 side, the coolant tubes 43a project toward the header tanks 75 more than the refrigerant tubes 12a project. In other words, the ends of the refrigerant tubes 12 a on theheader tanks 75 side and the ends of the coolant tubes 43 a on theheader tanks 75 side are arranged irregularly.

In contrast, at portions of the intermediate plate member 752corresponding to the refrigerant tubes 12 a which do not communicatewith the communicating spaces 76 out of the refrigerant tubes 12 a whichconstitute a part of the downstream heat exchanging portion 72, thirdthrough holes 752 d penetrating therethrough from the front to the backthereof are provided. The refrigerant tubes 12 a which do notcommunicate with the communicating spaces 76 out of the refrigeranttubes 12 a which constitute a part of the downstream heat exchangingportion 72 penetrates through the third through holes 752 d.Accordingly, the refrigerant tubes 12 a which do not communicate withthe communicating spaces 76 out of the refrigerant tubes 12 a whichconstitute a part of the downstream heat exchanging portion 72communicate with the downstream side refrigerant space 741 formed in thetank forming member 753.

Furthermore, as illustrated in FIG. 3, at ends of the downstream heatexchanging portion 72 on the header tanks 75 side, the refrigerant tubes12 a which do not communicate with the communicating spaces 76 projecttoward the header tanks 75 more than the refrigerant tubes 12 a thatcommunicate with the communicating spaces 76. In other words, the endsof the adjacent refrigerant tubes 12 a are arranged irregularly.

The center portion 753 c of each of the tank forming members 753 isformed into a shape matching the depressed portions 752 a formed on theintermediate plate member 752 and the upstream side coolant space 731and the downstream side refrigerant space 741 are partitioned so as toavoid the coolant or the refrigerant in the interior from leaking fromjoint portions between the header plate 751 and the intermediate platemember 752.

As illustrated in FIG. 2, a coolant outflow pipe 435 configured to flowout the coolant from the upstream side coolant space 731 is connected toone end side in the longitudinal direction (the left side of the paperplane of the drawing) of the upstream side tank units 73 arranged on oneend side in the longitudinal direction of the coolant tubes 43 a (theupper side of the paper plane of the drawing) (hereinafter referred toas a first upstream side tank unit 730 a). A coolant inflow pipe 434configured to flow the coolant into the upstream side coolant space 731is connected to the other end side in the longitudinal direction (theright side in the paper plane of the drawing) of the upstream side tankunits 73 arranged on the other end side in the longitudinal direction ofthe coolant tubes 43 a (the lower side of the paper plane of thedrawing) (hereinafter referred to as a second upstream side tank unit730 b).

A refrigerant outflow pipe 125 configured to flow out the refrigerantfrom the downstream side refrigerant space 741 is connected to one endside in the longitudinal direction (the left side of the paper plane ofthe drawing) of the downstream side tank units 74 arranged on one endside in the longitudinal direction of the refrigerant tubes 12 a (theupper side of the paper plane of the drawing) (hereinafter referred toas a first downstream side tank unit 740 a). A refrigerant inflow pipe124 configured to flow the refrigerant into the downstream siderefrigerant space 741 is connected to the other end side in thelongitudinal direction (the right side of the paper plane of thedrawing) of the downstream side tank units 74 arranged on the other endside in the longitudinal direction of the refrigerant tubes 12 a (thelower side of the paper plane of the drawing) (hereinafter, referred toas a second downstream side tank unit 740 b).

As illustrated in a schematic perspective view of FIG. 6, a firstdownstream side partitioning member 742 a configured to partition thedownstream side refrigerant space 741 into two parts in the longitudinaldirection of the first downstream side tank unit 740 a is arranged inthe first downstream side tank unit 740 a.

Hereinafter, a space communicating with the refrigerant tubes 12 a otherthan the most downstream refrigerant tubes 121 a out of the twodownstream side refrigerant spaces 741 partitioned by the firstdownstream side partitioning member 742 a is referred to as a firstdownstream side refrigerant space 741 a, and a space communicatingdirectly with the refrigerant outflow pipe 125 and communicating withthe most downstream refrigerant tubes 121 a is referred to as a seconddownstream side refrigerant space 741 b.

A second downstream side partitioning member 742 b configured topartition the downstream side refrigerant space 741 into two parts inthe longitudinal direction of the second downstream side tank unit 740 bis arranged in the second downstream side tank unit 740 b.

Hereinafter, a space communicating directly with the refrigerant inflowpipe 124 out of the two downstream side refrigerant spaces 741partitioned by the second downstream side partitioning member 742 b isreferred to as a third downstream side refrigerant space 741 c, and aspace communicating with both of the most downstream refrigerant tubes121 a and other refrigerant tubes 12 a is referred to as a fourthdownstream side refrigerant space 741 d.

Here, when viewing in an outside air flowing direction X, the firstdownstream side partitioning member 742 a is arranged on a side closerto the refrigerant outflow pipe 125 than the second downstream sidepartitioning member 742 b.

Therefore, in the heat exchanger 70 of the present embodiment, asillustrated in a schematic perspective view of FIG. 6, a part of therefrigerant flowing into the third downstream side refrigerant space 741c of the second downstream side tank unit 740 b via the refrigerantinflow pipe 124 flows into the refrigerant tubes 12 a which constitute apart of the second core portion 702 of the downstream heat exchangingportion 72, and flows from the lower side toward the upper side of thedrawing in the refrigerant tubes 12 a. Another part of the refrigerantflowing into the third downstream side refrigerant space 741 c of thesecond downstream side tank unit 740 b flows into the refrigerant tubes12 a which constitute a part of the second core portion 702 of theupstream heat exchanging portion 71 via the communicating spaces 76formed between the header plate 751 and the intermediate plate member752, and flows from the lower side toward the upper side in the drawingin the refrigerant tubes 12 a.

The refrigerant flowing out from the refrigerant tubes 12 a whichconstitute a part of the second core portion 702 of the downstream heatexchanging portion 72 is collected in the first downstream siderefrigerant space 741 a of the first downstream side tank unit 740 a.The refrigerant flowing out from the refrigerant tubes 12 a whichconstitute a part of the second core portion 702 of the upstream heatexchanging portion 71 is collected in the first downstream siderefrigerant space 741 a of the first downstream side tank unit 740 a viathe communicating spaces 76 formed between the header plate 751 and theintermediate plate member 752.

The refrigerant collected in the first downstream side refrigerant space741 a of the first downstream side tank unit 740 a flows from the rightside to the left side of the drawing. Subsequently, a part of therefrigerant collected in the first downstream side refrigerant space 741a of the first downstream side tank unit 740 a flows into therefrigerant tubes 12 a which constitute a part of the second coreportion 702 of the downstream heat exchanging portion 72, and flows fromthe upper side toward the lower side in the drawing in the refrigeranttubes 12 a. Another part of the refrigerant collected in the firstdownstream side refrigerant space 741 a of the first downstream sidetank unit 740 a flows into the refrigerant tubes 12 a which constitute apart of the second core portion 702 of the upstream heat exchangingportion 71 via the communicating spaces 76 formed between the headerplate 751 and the intermediate plate member 752, and flows from theupper side toward the lower side in the drawing in the refrigerant tubes12 a.

The refrigerant flowing out from the refrigerant tubes 12 a whichconstitute a part of the second core portion 702 of the downstream heatexchanging portion 72 is collected in the fourth downstream siderefrigerant space 741 d of the second downstream side tank unit 740 b.The refrigerant flowing out from the refrigerant tubes 12 a whichconstitute a part of the second core portion 702 of the upstream heatexchanging portion 71 is collected in the fourth downstream siderefrigerant space 741 d of the second downstream side tank unit 740 bvia the communicating spaces 76 formed between the header plate 751 andthe intermediate plate member 752.

The refrigerant collected in the fourth downstream side refrigerantspace 741 d of the second downstream side tank unit 740 b flows from theright side to the left side of the drawing. Subsequently, a part of therefrigerant collected in the fourth downstream side refrigerant space741 d of the second downstream side tank unit 740 b flows into the mostdownstream refrigerant tubes 121 a which constitute a part of the firstcore portion 701 of the downstream heat exchanging portion 72, and flowsfrom the lower side toward the upper side in the drawing in the mostdownstream refrigerant tubes 121 a. Another part of the refrigerantcollected in the fourth downstream side refrigerant space 741 d of thesecond downstream side tank unit 740 b flows into the most downstreamrefrigerant tubes 121 a which constitute a part of the first coreportion 701 of the upstream heat exchanging portion 71 via thecommunicating spaces 76 formed between the header plate 751 and theintermediate plate member 752, and flows from the lower side toward theupper side in the drawing in the most downstream refrigerant tubes 121a.

The refrigerant flowing out from the most downstream refrigerant tubes121 a which constitute a part of the first core portion 701 of thedownstream heat exchanging portion 72 is collected in the seconddownstream side refrigerant space 741 b of the first downstream sidetank unit 740 a. The refrigerant flowing out from the most downstreamrefrigerant tubes 121 a which constitute a part of the first coreportion 701 of the upstream heat exchanging portion 71 is collected inthe second downstream side refrigerant space 741 b of the firstdownstream side tank unit 740 a via the communicating spaces 76 formedbetween the header plate 751 and the intermediate plate member 752.

The refrigerant collected in the second downstream side refrigerantspace 741 b of the first downstream side tank unit 740 a flows from theright side to the left side of the drawing, and flows out from therefrigerant outflow pipe 125.

In contrast, in the heat exchanger 70 of the present embodiment, asillustrated in the schematic perspective view of FIG. 6, the coolantflowing into the upstream side coolant space 731 of the second upstreamside tank unit 730 b via the coolant inflow pipe 434 flows into thecoolant tubes 43 a which constitute a part of the upstream heatexchanging portion 71, and flows from the lower side toward the upperside of the drawing in the coolant tubes 43 a.

The coolant flowing out from the coolant tubes 43 a which constitute apart of the upstream heat exchanging portion 71 is collected in theupstream side coolant space 731 of the first upstream side tank unit 730a. The coolant collected in the upstream side coolant space 731 of thefirst upstream side tank unit 730 a flows from the right side to theleft side of the drawing, and flows out from the coolant outflow pipe435.

In the present embodiment, a flow channel total cross-sectional area ofthe plurality of most downstream refrigerant tubes 121 a which form afinal path (first core portion 701) of the refrigerant flow is smallerthan the flow-channel total sectional area of a plurality of second-mostdownstream refrigerant tubes 122 a (second-most downstream first tube)which form a path immediately before the refrigerant flow of the finalpath. In other words, when viewing the heat exchanger 70 from theoutside air flowing direction X, the length of the first core portion701 in the stacking direction of the tubes 12 a shorter than the heatexchange portion (a portion where the plurality of second-mostdownstream refrigerant tubes 122 a are arranged in a stacked manner)which constitute a part of the path immediately before the final path.

In the heat exchanger 70 described above, the refrigerant radiator 12includes both of the refrigerant tubes 12 a which constitute a part ofthe upstream heat exchanging portion 71 and the refrigerant tubes 12 awhich constitute a part of the downstream heat exchanging portion 72,and the radiator 43 includes the coolant tubes 43 a which constitute apart of the upstream heat exchanging portion

The respective components such as the refrigerant tubes 12 a of the heatexchanger 70, the coolant tubes 43 a, and the header tank 75 and theouter fins 70 b described above are all formed of the same metallicmaterial (aluminum alloy in the present embodiment). The header plate751 and the tank forming member 753 are fixed by caulking in a state inwhich the intermediate plate member 752 is interposed therebetween.

In addition, the heat exchanger 70 in a state of being fixed by caulkingis loaded entirely into a heating furnace and is heated, a brazingfiller metal in which the surface of the respective components are cladin advance is fused and then is cooled until the brazing filler metal issolidified again, so that the respective components are integrallybrazed. Accordingly, the refrigerant radiator 12 and the radiator 43 arecombined into one unit.

The refrigerant tubes 12 a may be used as an example of the first tubein which the first fluid flows, and the coolant tubes 43 a may be usedas an example of the second tube in which the second fluid flows. In thepresent embodiment, the refrigerant is used as an example of the firstfluid, and the coolant is used as an example of the second fluid.

Subsequently, an electric controller of the present embodiment will bedescribed. The air conditioning control apparatus includes a knownmicrocomputer including a CPU, a ROM, and a RAM and peripheral circuitsthereof, and is configured to perform various computations and processeson the basis of an air conditioning control program memorized in theROM, and control operations of the various air conditioning controldevices 11, 13, 41 connected to an output side thereof.

Also, various air conditioning control sensor group, such as an insideair sensor configured to detect a vehicle interior temperature, anoutside air sensor configured to detect the outside air temperature, asolar radiation sensor configured to detect the quantity of solarradiation in the vehicle interior, an evaporator-temperature sensorconfigured to detect the blown out air temperature of the refrigerantevaporator 16 (the temperature of the evaporator), a dischargedrefrigerant temperature sensor configured to detect the dischargedrefrigerant temperature from the compressor 11, an outlet refrigeranttemperature sensor configured to detect an outlet side refrigeranttemperature Te of the refrigerant radiator 12 is connected to an inputside of the air conditioning control apparatus.

Furthermore, an operation panel, which is not illustrated, which isarranged near the dashboard panel positioned at the front portion in thevehicle interior, is connected to the input side of the air conditioningcontrol apparatus, so that operation signals output from various airconditioning operation switches provided on the operation panel areinput. An operation switch of the vehicle air conditioning apparatus 1,a vehicle interior temperature setting switch configured to set thevehicle interior temperature, an operation mode selecting switch and thelike are provided as the various air conditioning operation switchesthat are mounted on the operation panel.

The air conditioning control apparatus includes control means configuredto control the electric motor 11 b and the like of the compressor 11integrally therewith, and is configured to control the operationsthereof. However, in the present embodiment, a configuration thatcontrols the operation of the compressor 11 (hardware and software) inthe air conditioning control apparatus constitute a part of refrigerantdischarging capacity control means.

In addition, the air conditioning control apparatus of the presentembodiment has a configuration (frost formation determining means) thatdetermines whether or not frost formation occurs in the refrigerantradiator 12 on the basis of a detection signal from an air conditioningcontrol sensor group described above. Specifically, in the frostformation determining means of the present embodiment, it is determinedthat the frost formation occurs in the refrigerant radiator 12 when thevehicle speed of the vehicle is not higher than a predeterminedreference vehicle speed (20 km/h in the present embodiment) and theoutlet side refrigerant temperature Te of the refrigerant radiator 12 isnot higher than 0° C.

Subsequently, an operation of the vehicle air conditioning apparatus 1of the present embodiment having the configuration described above willbe descried. When an operation switch of the vehicle air conditioningapparatus 1 of the operation panel is turned on (ON) in a state in whicha vehicle activation switch, which is not illustrated, is turned on(ON), the control apparatus executes a program for controlling the airconditioning memorized in a memory circuit in advance. When this programis executed, the control apparatus reads the detection signal from theair conditioning control sensor group described above and the operationsignal of the operation panel.

Subsequently, a target blowout temperature TAO that is a targettemperature of the air that is blown out into the vehicle interior iscalculated on the basis of values of the detection signals and theoperation signals. Further, the control device determines operatingstates of the various air conditioning control devices connected to theoutput side of the control apparatus on the basis of the calculatedtarget blowout temperature TAO and the detection signals of the sensorgroup.

For example, the refrigerant discharging capacity of the compressor 11,that is, a control signal to be output to the electric motor of thecompressor 11 is determined as described below. First, a targetevaporator blowout temperature TEO of the refrigerant evaporator 16 isdetermined on the basis of the target blowout temperature TAO withreference to a control map that is memorized in the control apparatus inadvance.

Subsequently, the control signal to be output to the electric motor ofthe compressor 11 is determined by using a feedback control method onthe basis of a deviation between the target evaporator blowouttemperature TEO and an blown out air temperature Te from the refrigerantevaporator 16 detected by a evaporator temperature sensor, so that theblown out air temperature from the refrigerant evaporator 16 gets closerto the target evaporator blowout temperature TEO.

The control signal output to the servo motor of the air mix door 34 isdetermined by referring the control map memorized in the controlapparatus in advance on the basis of the target blowout temperature TAOand the blown out air temperature from the refrigerant evaporator 16, sothat the temperature of air blown into the vehicle interior becomes anoccupant-desired temperature set by a vehicle interior temperaturesetting switch.

The control signals determined as described above are output to thevarious air conditioning control devices. After that, until the stop ofthe operation of the vehicle air conditioning apparatus 1 is required bythe operation panel, a control routine, which includes the reading ofthe above-mentioned detection signals and the above-mentioned operationsignals the calculation of the target blowout temperature TAO thedetermination of the operating states of the various air conditioningcontrol devices, the output of the control voltages and the controlsignals, is repeated every predetermined control period.

Therefore, in the heat pump cycle 10, the discharged refrigerantdischarged from the compressor 11 flows into the refrigerant radiator 12and radiates heat by the heat exchange with the outside air blown fromthe blower fan 13. According to the test and examination performed bythe present inventors, in the heat pump cycle 10, the pressure of thedischarged refrigerant becomes not lower than a reference refrigerantpressure P1 (specifically, approximately 1.5 MPa), and the surfacetemperature (the wall surface temperature) of the refrigerant tubes 12 aof the refrigerant radiator 12 in this case is known to be increased toa range on the order of 60° C. to 65° C. by a high-temperaturerefrigerant discharged from the compressor 11.

The refrigerant flowed out from the refrigerant radiator 12 is separatedinto gas and liquid by the receiver 14. A liquid-phase refrigerantflowed out from the receiver 14 is decompressed and expanded until alow-pressure refrigerant is achieved by the temperature type expansionvalve 15. At this time, in the temperature type expansion valve 15, avalve opening is adjusted so that the degree of superheat of therefrigerant on the outlet side of the refrigerant evaporator 16 fallswithin a predetermined range set in advance.

The low-pressure refrigerant decompressed and expanded by thetemperature type expansion valve 15 flows into the refrigerantevaporator 16 and evaporates by absorbing heat from the blown air thatis blown by the blower 32. Accordingly, the blown air blown into thevehicle interior is cooled. The refrigerant having flowed out from therefrigerant evaporator 16 is sucked into the compressor 11 and iscompressed again.

In contrast, the temperature of the blown air (cold wind) cooled by therefrigerant evaporator 16 is adjusted by heating the blown air (coldwind) of an air volume in accordance with the opening degree of the airmix door 34 with the electric heater 36, and mixing with the blown airflowing in the mixing space 35 so as to bypass the electric heater 36.Subsequently, the air conditioning wind adjusted in temperature is blownout from the mixing space 35 into the vehicle interior via therespective outlets.

In the case where an inside air temperature of the vehicle interior iscooled to a temperature lower than an outside air temperature by the airconditioning wind blown into the vehicle interior, the cooling of thevehicle interior is achieved, while in the case where the inside airtemperature is heated to a temperature higher than the outside airtemperature, the heating of the vehicle interior is achieved.

As described above, in the present embodiment, the final path of therefrigerant flow is determined to be the first core portion 701 formedonly by the most downstream refrigerant tubes 121 a, and the first coreportion 701 constitutes a part of the subcooling portion. Therefore, thecoolant side heat connecting portions 72 b is not provided on the outerfins 70 b arranged in the first core portion 701, and the number of therefrigerant side heat connecting portions 71 b is larger than the numberof the coolant side heat connecting portions 72 b. Accordingly, theouter fins 70 b arranged in the first core portion 701 are used entirelyfor radiating heat of the discharged refrigerant to the outside air.

Therefore, according to the present embodiment, heat of the dischargedrefrigerant flowing in the most downstream refrigerant tubes 121 a isradiated sufficiently to the outside air in the first core portion 701,so that the refrigerant on the outlet side of the refrigerant radiator12 has a desired degree of subcooling.

Therefore, the most downstream refrigerant tubes 121 a which constitutea part of the subcooling portion (the first core portion 701) having anextremely low heat transmitting rate does not need to be increased inlength, that is, the refrigerant tubes 12 a which constitute a part ofthe condenser (second core portion 702) having a high heat transmittingrate does not need to be decreased in length, so that lowering of theheat exchanging performance of the heat exchanger 70 as a whole may berestrained.

Here, the relationship between the degree of subcooling and theheat-radiating capacity of the refrigerant in the composite-type heatexchanger is illustrated in FIG. 7. In FIG. 7, a result of experiment ofthe composite-type heat exchanger 70 of the present embodiment is shownby a square plot. A result of experiment of a heat exchanger of acomparative example in which the first core portion 701 is not providedand the coolant tubes 43 a are arranged over the entire area of the heatexchanger is shown by a triangle plot.

As illustrated in FIG. 7, in the composite-type heat exchanger, when anattempt is made to obtain a predetermined degree of subcooling, sincethe heat exchanger of the comparative example is affected by heatradiation on the coolant side, so that the heat-radiating capacity ofthe refrigerant is lowered. In contrast, as in the present embodiment,the heat-radiating capacity of the refrigerant can be improved byproviding the first core portion 701.

In the present embodiment, the refrigerant tubes 12 a and the coolanttubes 43 a which constitute a part of the second core portion 702 arearranged alternately in a stacked manner, and the refrigerant tubes 12 aand the coolant tubes 43 a are thermally connected by the outer fins 70b. Therefore, in the case where a surface temperature of the coolanttubes 43 a and a surface temperature of the refrigerant tubes 12 a aredifferent, a range used for radiating heat of the coolant to the outsideair and a range for radiating heat of the refrigerant to the outside airin the outer fins 70 b are adjusted depending on the temperaturedifference, and the heat of the coolant and the heat of the dischargedrefrigerant are radiated adequately to the outside air.

For example, in the case where the heat of the coolant out of thecoolant and the discharged refrigerant needs to be radiated, the surfacetemperature of the coolant tubes 43 a is increased, and the temperaturedifference from the outside air becomes larger in comparison with therefrigerant tubes 12 a. At this time, the range used for radiating theheat of the coolant to the outside air becomes larger than the range forradiating the heat of the refrigerant to the outside air in the outerfins 70 b, and the heat of the coolant is radiated to the outside air.

Therefore, in the refrigerant radiator 12, the heat of the dischargedrefrigerant can be radiated to the outside air, and in the radiator 43,the heat of the coolant can be radiated to the outside air.Consequently, an adequate heat exchange is achieved between a pluralityof types of fluids.

Here, in the refrigerant tubes 12 a and the coolant tubes 43 a whichconstitute a part of the second core portion 702 of the downstream heatexchanging portion 72 out of the upstream heat exchanging portion 71 andthe downstream heat exchanging portion 72, the difference between thesurface temperature of the both tubes 12 a, 43 a, and the outside airtemperature is reduced, and the adjustment of the range used forradiating the heat of the coolant to the outside air and the range forradiating heat of the refrigerant to the outside air in accordance withthe temperature difference in the outer fins 70 b becomes lesseffective.

In contrast, in the present embodiment, the refrigerant tubes 12 a andthe coolant tubes 43 a which constitute at least the second core portion702 of the upstream heat exchanging portion 71 out of the upstream heatexchanging portion 71 and the downstream heat exchanging portion 72 arearranged alternately in a stacked manner. Accordingly, the range usedfor radiating the heat of the coolant to the outside air and the rangefor radiating the heat of the refrigerant to the outside air in theouter fins 70 b are adjusted in accordance with the temperaturedifference, so that the heat of the coolant and the heat of thedischarged refrigerant can be radiated adequately to the outside air.

In the present embodiment, the dummy tubes 77 in which neither therefrigerant nor the coolant flows are arranged between the mostdownstream refrigerant tubes 121 a which form the first core portion 701and the coolant tubes 43 a which form the second core portion 702.Therefore, breakage of the tubes 12 a, 43 a or the header tank 75 bygeneration of a heat stress in association with a heat distortion of thetubes 12 a, 43 a or the header tank 75 occurring due to a difference inamount of thermal expansion caused by the temperature difference betweenthe refrigerant flowing in the most downstream refrigerant tubes 121 aand the coolant flowing in the coolant tubes 43 a can be restrained.

Since the liquid-phase refrigerant flows in the most downstreamrefrigerant tubes 121 a in the first core portion 701 which constitutesa part of the subcooling portion, a pressure loss of the refrigerant issmall, but the flow velocity is low and the heat transmitting rate issmall.

In contrast, in the present embodiment, the flow channel totalcross-sectional area of the plurality of most downstream refrigeranttubes 121 a which form the final path (the first core portion 701) ofthe refrigerant flow is smaller than the flow channel totalcross-sectional area of the plurality of second-most downstreamrefrigerant tubes 122 a which form the path immediately before the finalpath. In this configuration, the flow velocity of the refrigerant in thefirst core portion 701 can be increased to improve the heat exchangingperformance of the first core portion 701. Therefore, the area of thefirst core portion 701 does not need to be increased for obtaining adesired degree of subcooling, and hence the heat exchanging performanceof the heat exchanger 70 as a whole can be improved by increasing thearea of the second core portion 702.

Second Embodiment

Subsequently, a second embodiment of the present disclosure will bedescribed with reference to FIG. 8. In comparison with the firstembodiment described above, the second embodiment is different in apoint that a first core portion 701 includes also a coolant tube 43 a.In FIG. 8, refrigerant tubes 12 a are illustrated with diagonal hatchingand the coolant tube 43 a is illustrated by dot hatching for clarifyingthe drawing.

As illustrated in FIG. 8, the first core portion 701 of a composite-typeheat exchanger 70 of the present embodiment is provided with the coolanttube 43 a. In the present embodiment, although the number of therefrigerant tubes 12 a (nine in this example) is larger than the numberof the coolant tube 43 a (one in this example) in the first core portion701. Surfaces of outer fins 70 b are provided with a plurality ofshutter-like louvers 700 formed along the flowing direction of theoutside air by cutting and rising.

In the outer fin 70 b between the most downstream refrigerant tube 121 aand the coolant tube 43 a adjacent thereto in a stacking direction ofthe tubes 12 a, 43 a, a first slit hole 70 c penetrating through theouter fin 70 b from the front to the back and extending in the flowingdirection of the outside air is formed. With the first slit hole 70 c,heat transfer between the most downstream refrigerant tube 121 a and thecoolant tube 43 a adjacent to each other in the stacking direction ofthe tubes 12 a, 43 a is restricted.

A second slit hole 70 d extending in the stacking direction of the tubes12 a, 43 a is formed at a center portion in the flowing direction of theoutside air of the outer fins 70 b arranged between the most downstreamrefrigerant tube 121 a and the coolant tube 43 a adjacent to each other.With the second slit hole 70 d, heat transfer between the mostdownstream refrigerant tube 121 a and the coolant tube 43 a adjacent toeach other in the flowing direction of the outside air is restricted.

Therefore, the first slit hole 70 c and the second slit hole 70 d of thepresent embodiment are used as an example of a heat-shielding portion ofthe present disclosure. The first slit hole 70 c and the second slithole 70 d may be connected to each other.

In the present embodiment, even in the case where the first core portion701 is provided with the coolant tube 43 a, the outer fins 70 b arrangedbetween the most downstream refrigerant tube 121 a and the coolant tube43 a are provided with the first slit holes 70 c and the second slitholes 70 d, so that the heat transfer between the most downstreamrefrigerant tubes 121 a and the coolant tube 43 a is restricted. Inother words, the outer fins 70 b arranged on the first core portion 701is provided only with the refrigerant side heat connecting portions 71b, and the coolant side heat connecting portions 72 b is not provided.

Therefore, in the outer fins 70 b arranged in the first core portion701, since the number of the refrigerant side heat connecting portions71 b is larger than the number of the coolant side heat connectingportions 72 b, the same effects and advantages as those of the firstembodiment described above can be obtained.

Third Embodiment

Subsequently, a third embodiment of the present disclosure will bedescribed with reference to FIG. 9. The third embodiment is different inthe flow of the refrigerant of the first core portion 701 in comparisonwith the first embodiment.

As illustrated in FIG. 9, an upstream side partitioning member 732 aconfigured to partition the upstream side coolant space 731 in theinternal space of the second upstream side tank unit 730 b into twoparts in the longitudinal direction is arranged in the second upstreamside tank unit 730 b. A space closer to the first core portion 701 (theleft side on the paper plane) out of the two internal spaces of the tankpartitioned by the upstream side partitioning member 732 a (hereinafter,referred to as an upstream side refrigerant space 731 a) communicateswith the most downstream refrigerant tubes 121 a, but not communicatewith coolant tube 43 a. A refrigerant outflow pipe 125 is connected tothe upstream side refrigerant space 731 a.

In the present embodiment, the refrigerant collected in the fourthdownstream side refrigerant space 741 d of the second downstream sidetank unit 740 b flows into the most downstream refrigerant tubes 121 awhich constitute a part of the first core portion 701 of a downstreamheat exchanging portion 72, and flows from a lower side toward an upperside in the drawing in the most downstream refrigerant tubes 121 a. Therefrigerant flowing out from the most downstream refrigerant tubes 121 awhich constitute a part of the first core portion 701 of the downstreamheat exchanging portion 72 flows into the most downstream refrigeranttubes 121 a which constitute a part of the first core portion 701 of anupstream heat exchanging portion 71 via a communicating spaces 76 formedbetween a header plate 751 and an intermediate plate member 752, andflows from the upper side toward the lower side in the drawing in themost downstream refrigerant tubes 121 a.

The refrigerant flowing out from the most downstream refrigerant tubes121 a which constitute a part of the first core portion 701 of theupstream heat exchanging portion 71 is collected in the upstream siderefrigerant space 731 a of the second upstream side tank unit 730 b. Therefrigerant collected in the upstream side refrigerant space 731 a ofthe second upstream side tank unit 730 b flows from the right side tothe left side of the drawing, and flows out from the refrigerant outflowpipe 125.

As described thus far, in the present embodiment, the refrigerantflowing out from the most downstream refrigerant tubes 121 a whichconstitute a part of the downstream heat exchanging portion 72 in thefirst core portion 701 flows into the most downstream refrigerant tubes121 a which constitute a part of the upstream heat exchanging portion71. In other words, a flowing direction of the refrigerant and a flowingdirection of the outside air in the first core portion 701 oppose eachother. Therefore, heat of the refrigerant flowing in the most downstreamrefrigerant tubes 121 a may be radiated to the outside air with highefficiency in the first core portion 701.

Fourth Embodiment

Subsequently, a fourth embodiment of the present disclosure will bedescribed with reference to FIG. 10. The present embodiment is differentin the coolant flow in the heat exchanger 70 in comparison with thefirst embodiment.

As illustrated in FIG. 10, a coolant outflow pipe 435 configured toallow the coolant to flow out from the upstream side coolant space 731is connected to one end side (the left side of the paper plane in thedrawing) in a longitudinal direction of the second upstream side tankunit 730 b. A coolant inflow pipe 434 configured to flow the coolantinto the upstream side coolant space 731 is connected to the other endside (the right side of the paper plane in the drawing) in thelongitudinal direction of the first upstream side tank unit 730 a.

Therefore, in the heat exchanger 70 of the present embodiment, thecoolant flowing into the upstream side coolant space 731 of the firstupstream side tank unit 730 a via the coolant inflow pipe 434 flows intothe coolant tubes 43 a which constitute a part of the upstream heatexchanging portion 71, and flows from the upper side toward a lower sidein the drawing in the coolant tubes 43 a.

The coolant flowing out from the coolant tubes 43 a which constitute apart of the upstream heat exchanging portion 71 is collected in theupstream side coolant space 731 of the second upstream side tank unit730 b. The coolant collected in the upstream side coolant space 731 ofthe second upstream side tank unit 730 b flows from the right side tothe left side in the drawing, and flows out from the coolant outflowpipe 435.

In the present embodiment, a flowing direction of the refrigerantflowing in an second-most downstream refrigerant tubes 122 a and aflowing direction of the coolant flowing in the coolant tubes 43 aarranged adjacent to the second-most downstream refrigerant tubes 122 abecome the same direction. In other words, the flowing direction of therefrigerant flowing in the second-most downstream refrigerant tubes 122a and the flowing direction of the coolant flowing in the coolant tubes43 a arranged adjacent to the second-most downstream refrigerant tubes122 a are parallel to each other.

According to the present embodiment, in a path immediately before afinal path of the refrigerant flow, the refrigerant flowing in thesecond-most downstream refrigerant tubes 122 a and the coolant flowingin the coolant tubes 43 a can be restricted from performing thermalexchange via an outer fins 70 b. Therefore, the refrigerant immediatelybefore flowing into a first core portion 701 can be prevented from beingheated by heat of the coolant.

Fifth Embodiment

Subsequently, a fifth embodiment of the present disclosure will bedescribed with reference to FIG. 11 to FIG. 13. In the presentembodiment, an example in which configurations of a heat pump cycle 10and a coolant circulation circuit 40 of the first embodiment aremodified as illustrated in general configuration drawings in FIG. 11 toFIG. 13 will be described.

The heat pump cycle 10 of the present embodiment is a vapor compressionrefrigeration cycle having a function of heating or cooling air blowninto a vehicle interior, which is a space to be air-conditioned, in avehicle air conditioning apparatus 1. Therefore, the heat pump cycle 10is capable of switching the refrigerant flow channel to execute aheating operation (a heat-up operation) for warming the vehicle interiorby heating the air blown to the vehicle interior, which is an objectfluid of heat exchange, and a cooling operation (refrigeratingoperation) for cooling the air blown to the vehicle interior to cool thevehicle interior.

In addition, in the heat pump cycle 10, a defrosting operation formelting and removing frost adhered to an outdoor heat exchanger 160 of acomposite-type heat exchanger 70, which will be described later,configured to function as a evaporator for evaporating the refrigerantat the time of heating operation can be executed. In the generalconfiguration drawings illustrated in the heat pump cycle 10 of FIG. 11to FIG. 13, flows of the refrigerant at the time of respectiveoperations are indicated by an arrow of a solid line.

A refrigerant inlet side of an indoor condenser 120 as the using sideheat exchanger is connected to a refrigerant discharge port of acompressor 11. The indoor condenser 120 is a heating heat exchangerarranged in the interior of a casing 31 of an indoor air conditioningunit 30 of the vehicle air conditioning apparatus 1 and configured tocause a high-temperature high-pressure refrigerant flowing in theinterior thereof and the air blown to the vehicle interior after thepassage through an indoor evaporator 20, which will be described later,to change heat with each other. A detailed configuration of the indoorair conditioning unit 30 will be described later.

A warming fixed throttle 130 as decompression means for the heatingoperation configured to decompress and expand the refrigerant flowingout from the indoor condenser 120 at the time of the heating operationis connected to the refrigerant outlet side of the indoor condenser 120.Examples of the warming fixed throttle 130 which can be employed hereinclude a orifice and a capillary tube. A refrigerant inlet side of theoutdoor heat exchanger 160 of the composite-type heat exchanger 70 isconnected to an outlet side of the warming fixed throttle 130.

Furthermore, a fixed throttle bypassing passage 140 configured to causethe refrigerant flowing from the indoor condenser 120 to bypass thewarming fixed throttle 130 and guide the refrigerant on the outdoor heatexchanger 160 side is connected to the refrigerant outlet side of theindoor condenser 120. The fixed throttle bypassing passage 140 isarranged with an opening-and-closing valve 15 a configured to open andclose the fixed throttle bypassing passage 140. The opening-and-closingvalve 15 a is an electromagnetic valve an opening and closing operationof which is controlled by a control voltage output from the airconditioning control apparatus.

A pressure loss generating when the refrigerant passes through theopening-and-closing valve 15 a is extremely smaller than a pressure lossgenerating when the refrigerant passes through the fixed throttle 130.Therefore, the refrigerant flowing out from the indoor condenser 120flows into the outdoor heat exchanger 160 via the fixed throttlebypassing passage 140 side when the opening-and-closing valve 15 a isopened, and flows into the outdoor heat exchanger 160 via the warmingfixed throttle 130 when the opening-and-closing valve 15 a is closed.

Accordingly, the opening-and-closing valve 15 a can switch therefrigerant flow channel of the heat pump cycle 10. Therefore, theopening-and-closing valve 15 a of the present embodiment has a functionas refrigerant flow channel switching means. Examples of the refrigerantflow channel switching means configured as described above which may beemployed here include an electric three-direction valve configured toswitch a refrigerant circuit that connects the outlet side of the indoorcondenser 120 and the inlet side of the warming fixed throttle 130 and arefrigerant circuit that connects the outlet side of the indoorcondenser 120 and the inlet side of the fixed throttle bypassing passage140.

The outdoor heat exchanger 160 is a heat exchange portion configured tocause the refrigerant flowing in the interior in the heat exchanger 70and outside air blown from a blower fan 17 to exchange heat with eachother. The outdoor heat exchanger 160 is arranged in an engine room andfunctions as an evaporating heat exchanger (evaporator) configured toevaporate the low-pressure refrigerant to bring out a heat absorbingeffect at the time of the heating operation, and functions as aradiation heat exchanger (radiator) configured to radiate heat from ahigh-pressure refrigerant at the time of the cooling operation.

The blower fan 17 is an electric blower of which an operation rate, thatis, a number of rotations (an amount of blown air) is controlled by thecontrol voltage output from the air conditioning control apparatus.

Furthermore, the heat exchanger 70 of the present embodiment integrallyincludes a radiator 43, which will be described later, configured tocause the coolant for cooling the above-described outdoor heat exchanger160 and a traveling electric motor MG and the outside air blown from theblower fan 17 to exchange heat with each other.

Therefore, the blower fan 17 of the present embodiment constitutes apart of exterior blowing means configured to blow the outside air towardboth of the outdoor heat exchanger 160 and the radiator 43. Since adetailed configuration of the composite-type heat exchanger 70 in whichthe exterior heat exchanger 160 and the radiator 43 are integrallyformed is the same as that of the first embodiment described above,detailed description will be omitted. However, specifically, therefrigerant radiator 12 of the first embodiment out of thecomposite-type heat exchanger 70 functions as the exterior heatexchanger 160.

An electric three-direction valve 15 b is connected to the outlet sideof the outdoor heat exchanger 160. The three-direction valve 15 b iscontrolled in operation by a control voltage output from the airconditioning control apparatus and constitutes a part of the refrigerantflow channel switching means together with the above-describedopening-and-closing valve 15 a. In the air conditioning controlapparatus, a configuration configured to control operations of thevarious devices 15 a, 15 b which constitute a part of the refrigerantflow channel switching means constitutes a part of the refrigerant flowchannel control means and a configuration configured to control anoperation of a three-direction valve 42 which constitutes a part of thecoolant circuit switching means constitutes a part of coolant circuitcontrol means. An outlet refrigerant temperature sensor 51 configured todetect an outlet side coolant temperature Te of the exterior heatexchanger 160 is provided.

More specifically, the three-direction valve 15 b is configured toswitch the flow channel to a refrigerant flow channel that connects theoutlet side of the outdoor heat exchanger 160 and an inlet side of anaccumulator 18, which will be described later, at the time of theheating operation, and to the refrigerant flow channel that connects theoutlet side of the outdoor heat exchanger 160 and an inlet side of acooling fixed throttle 19 at the time of the cooling operation.

The cooling fixed throttle 19 is decompression means for the coolingoperation that decompresses and expands the refrigerant flowed out fromthe outdoor heat exchanger 160 at the time of the cooling operation, andthe basic configuration is the same as that of the warming fixedthrottle 130. The refrigerant inlet side of the indoor evaporator 20 isconnected to the outlet side of the cooling fixed throttle 19.

The indoor evaporator 20 is a heat exchanger for cooling which isarranged on an upstream side of the indoor condenser 120 in thedirection of the air flow within the casing 31 of the indoor airconditioning unit 30, and configured to cause the refrigerant flowing inthe interior thereof and the air blown to the vehicle interior toexchange heat with each other to cool the air blown to the vehicleinterior. The inlet side of the accumulator 18 is connected to therefrigerant outlet side of the indoor evaporator 20.

The accumulator 18 is a gas-liquid separator for the low-pressure siderefrigerant that separates gas and liquid in the refrigerant flowingtherein and accumulates a surplus refrigerant in the cycle. An intakeside of the compressor 11 is connected to a gas-phase refrigerant outletof the accumulator 18. Therefore, the accumulator 18 has a function ofrestricting the liquid phase refrigerant from being sucked into thecompressor 11, and preventing a liquid compression of the compressor 11.

In the heat pump cycle 10 of the present embodiment, the temperature ofthe coolant flowing out from the radiator 43 of the heat exchanger 70 atthe time of the cooling operation becomes lower than the temperature ofthe refrigerant flowing out from the outdoor heat exchanger 160 of theheat exchanger 70. Accordingly, at the time of the cooling operation inwhich the outdoor heat exchanger 160 functions as a heat radiating heatexchange portion configured to radiate heat of the high-pressurerefrigerant, the degree of subcooling of the refrigerant flowing outfrom the outdoor heat exchanger 160 can be increased, so that animprovement of the cycle efficiency is achieved.

In contrast, in the heat pump cycle 10 of the present embodiment, thetemperature of the coolant in the interior of the radiator 43 of theheat exchanger 70 at the time of the heating operation becomes higherthan the temperature of the refrigerant flowing out from the outdoorheat exchanger 160 of the heat exchanger 70. Accordingly, at the time ofthe heating operation in which the outdoor heat exchanger 160 functionsas the evaporating heat exchanger which brings out the heat absorbingeffect by evaporating the low-pressure refrigerant, the heat of thecoolant is absorbed and hence the refrigerant is heated, so that theevaporation of the refrigerant is promoted.

Subsequently, the indoor air conditioning unit 30 will be described onlyon portions different from the first embodiment. The indoor airconditioning unit 30 is arranged inside of a dashboard panel (aninstrument panel) in a foremost portion of the vehicle interior, andincludes a blower 32, the above-described indoor condenser 120 and theindoor evaporator 20 accommodated in the casing 31 which forms an outershell thereof.

The indoor evaporator 20 and the indoor condenser 120 are arranged inthis order with respect to the flow of air blown to the vehicle interioron the downstream side of the blower 32 in the direction of the airflow. In other words, the indoor evaporator 20 is arranged on theupstream side of the indoor condenser 120 in the flowing direction ofthe air blown to the vehicle interior.

Further, an air mixture door 34 that adjusts a proportion of the airvolume that passes through the indoor condenser 120 to the blown airthat has passed through the indoor evaporator 20 is arranged on thedownstream side of the indoor evaporator 20 in the direction of the airflow, and on the upstream side of the indoor condenser 120 in thedirection of the air flow. Also, a mixing space 35 that mixes the blownair that has been heated by conducting heat exchange with therefrigerant in the indoor condenser 120 with the blown air that has notbeen heated while bypassing the indoor condenser 120 is provided on thedownstream side of the indoor condenser 120 in the direction of the airflow.

Subsequently, the coolant circulation circuit 40 will be described onlyon portions different from the first embodiment. The coolant circulationcircuit 40 includes a coolant pump 41, an electric three-direction valve42, a radiator 43 of the composite-type heat exchanger 70, and a bypasspassage 44 configured to flow the coolant so as to bypass the radiator43 arranged therein. A coolant temperature sensor 52 configured todetect a coolant temperature is arranged on an outlet side of thecoolant pump 41.

The three-direction valve 42 switches the coolant circuit between acoolant circuit that connects an inlet side of the coolant pump 41 andan outlet side of the radiator 43 to cause the coolant to flow into theradiator 43, and a coolant circuit that connects the inlet side of thecoolant pump 41 and an outlet side of the bypass passage 44 to cause thecoolant to flow while bypassing the radiator 43. The three-directionvalve 42 is controlled in operation by a control voltage output from theair conditioning control apparatus and constitutes a part of circuitswitching means for the coolant circuit. The three-direction valve 42also has a function as coolant inflow rate control means configured tocontrol the inflow rate of the coolant into the radiator 43 by switchingthe coolant circuit.

In other words, in the coolant circulation circuit 40 of the presentembodiment, as illustrated by broken line arrows in FIG. 11 so forth, acoolant circuit that circulates the coolant in the order of the coolantpump 41 the traveling electric motor MG the radiator 43 the coolant pump41, and a coolant circuit that circulates the coolant in the order ofthe coolant pump 41 the traveling electric motor MG the bypass passage44 the coolant pump 41 can be switched.

Therefore, when the three-direction valve 42 switches the circuit to thecoolant circuit in which the coolant flows so as to bypass the radiator43 during an operation of the traveling electric motor MG, the coolantdoes not radiate heat in the radiator 43, and increases in temperaturethereof. In other words, when the three-direction valve 42 switches thecircuit to the coolant circuit that allows the coolant to bypass theradiator 43, the heat of the traveling electric motor MG (amount of heatgeneration) is accumulated in the coolant.

In the coolant circulation circuit 40 of the present embodiment, thetemperature of the coolant flowing out from the radiator 43 of the heatexchanger 70 is not higher than a predetermined reference temperature(not higher than 65° C. in the present embodiment). Accordingly, aninverter of the traveling electric motor MG can be protected from a highheat.

The outdoor heat exchanger 160 is arranged in the engine room, andfunctions as the radiation heat exchanger which causes the coolant andthe outside air blown from the blower fan 17 to exchange heat with eachother. As described above, the radiator 43 constitutes a part of thecomposite-type heat exchanger 70 together with the outdoor heatexchanger 160.

Subsequently, an operation of the vehicle air conditioning apparatus 1of the present embodiment having the configuration described above willbe descried. The vehicle air conditioning apparatus 1 of the presentembodiment is capable of executing the heating operation for heating thevehicle interior and the cooling operation for cooling the vehicleinterior, as well as the defrosting operation at the time of the heatingoperation. Next, the operation of the above-mentioned operations will bedescribed.

(a) Heating Operation

The heating operation starts when a heating mode is selected by a selectswitch in a state in which an operation switch of the operation panelturns on (ON). In the case where it is determined that frost formationoccurs in the outdoor heat exchanger 160 by frost formation determiningmeans at the time of the heating operation, the defrosting operation isexecuted.

First of all, in the normal heating operation, the air conditioningcontrol apparatus closes the opening-and-closing valve 15 a, switchesthe three-direction valve 15 b to the refrigerant flow channel thatconnects the outlet side of the outdoor heat exchanger 160 and the inletside of the accumulator 18 and further activate the coolant pump 41 topump a predetermined flow rate of the coolant, and switches the circuitto the coolant circuit in which the coolant flows through thethree-direction valve 42 of the coolant circulation circuit 40 whilebypassing the radiator 43.

Accordingly, the heat pump cycle 10 is switched to the refrigerant flowchannel in which the refrigerant flows as indicated by solid line arrowsin FIG. 11, and the coolant circulation circuit 40 is switched to thecoolant circuit in which the coolant flows as indicated by dot linearrows in FIG. 11.

In the configurations of the refrigerant flow channel and the coolantcircuit, the air conditioning control apparatus reads the detectionsignals from the above-described air conditioning control sensor group,and the operation signals of the operation panel. Subsequently, a targetblowout temperature TAO that is a target temperature of the air that isblown out into the vehicle interior is calculated on the basis of valuesof the detection signals and the operation signals.

Further, the operating states of the various air conditioning controldevices connected to the output side of the air conditioning controlapparatus is determined on the basis of the calculated target blowouttemperature TAO and the detection signals of the sensor group.

For example, the refrigerant discharging capacity of the compressor 11,that is, a control signal to be output to the electric motor of thecompressor 11 is determined as described below. First, a targetevaporator blowout temperature TEO of the indoor evaporator 20 isdetermined on the basis of the target blowout temperature TAO withreference to a control map that is memorized in the air conditioningcontrol apparatus in advance.

Subsequently, the control signal to be output to the electric motor ofthe compressor 11 is determined by using a feedback control method onthe basis of a deviation between the target evaporator blowouttemperature TEO and an blown out air temperature from the indoorevaporator 20 detected by an evaporator temperature sensor, so that theblown out air temperature from the indoor evaporator 20 gets closer tothe target evaporator blowout temperature TEO.

A control signal output to the servo motor of the air mix door 34 isdetermined by using the target blowout temperature TAO, an blown out airtemperature from the indoor evaporator 20, the discharged refrigeranttemperature of the compressor 11 detected by a discharged refrigeranttemperature sensor, and the like, so that the temperature of air blowninto the vehicle interior becomes an occupant desired temperature set bya vehicle interior temperature setting switch.

At the time of the normal heating operation and the defrostingoperation, the opening degree of the air mix door 34 may be controlledso that the total air volume of the air blown to the vehicle interiorfrom the blower 32 passes through the indoor condenser 120.

The control signals determined as described above are output to variousair conditioning control devices. After that, until the stop of theoperation of the vehicle air conditioning apparatus 1 is required by theoperation panel, a control routine, which includes the reading of theabove-mentioned detection signals and the above-mentioned operationsignals the calculation of the target blowout temperature TAO thedetermination of the operating states of the various air conditioningcontrol devices, the output of the control voltages and the controlsignals, is repeated every predetermined control period.

Meanwhile, the repetition of this control routine is also performedbasically in the same manner at the time of other operations.

In the heat pump cycle 10 at the time of the normal heating operation, ahigh-pressure refrigerant discharged from the compressor 11 flows intothe indoor condenser 120. The refrigerant flowing into the indoorcondenser 120 radiates heat by exchanging heat between itself and theair that has been blown from the blower 32 and passed through the indoorevaporator 20 to the vehicle interior. Accordingly, the air blown to thevehicle interior is heated.

The high-pressure refrigerant flowing out from the indoor condenser 120flows into the warming fixed throttle 130 and decompressed and expandedsince the opening-and-closing valve 15 a is closed. The low-pressurerefrigerant decompressed and expanded by the warming fixed throttle 130flows into the outdoor heat exchanger 160. The low-pressure refrigerantflowing into the outdoor heat exchanger 160 absorbs heat from theoutside air blown by the blower fan 17, and then evaporates.

At this time, in the coolant circulation circuit 40, since the circuitis switched to the coolant circuit in which the coolant flows whilebypassing the radiator 43, the coolant is prevented from radiating heatto the refrigerant flowing in the outdoor heat exchanger 160 and thecoolant is prevented from absorbing heat from the refrigerant flowing inthe outdoor heat exchanger 160. In other words, the refrigerant flowingin the outdoor heat exchanger 160 is not thermally influenced by thecoolant.

The refrigerant flowing out from the outdoor heat exchanger 160 flowsinto the accumulator 18 and is separated into gas and liquid since thethree-direction valve 15 b is switched to the refrigerant flow channelwhich connects the outlet side of the outdoor heat exchanger 160 and theinlet side of the accumulator 18. A gas-phase refrigerant that has beenseparated by the accumulator 18 is absorbed by the compressor 11, andagain compressed.

As described thus far, at the normal heating operation, the air blown tothe vehicle interior is heated by the heat of the refrigerant dischargedfrom the compressor 11 by the indoor condenser 120, so that the vehicleinterior may be heated.

(b) Defrosting Operation

Subsequently, the defrosting operation will be described. In arefrigeration cycle device configured to cause the refrigerant and theoutside air to exchange heat in the outdoor heat exchanger 160 toevaporate the refrigerant as the heat pump cycle 10 of the presentembodiment, when the refrigerant evaporation temperature in the outdoorheat exchanger 160 is decreased to the frost formation temperature (0°C., specifically) or below, the frost formation may occur in the outdoorheat exchanger 160.

If such frost formation occurs, an outside air passage 70 a of the heatexchanger 70 is clogged by the frost, so that the heat exchangeperformance of the outdoor heat exchanger 160 is significantly lowered.Therefore, in the heat pump cycle 10 of the present embodiment, in thecase where the frost formation determining means determines that frostformation occurs in the outdoor heat exchanger 160 at the time of theheating operation, the defrosting operation is executed.

In this defrosting operation, the air conditioning control apparatusstops the operation of the compressor 11, and stops the operation of theblower fan 17. Therefore, at the time of the defrosting operation, therefrigerant flow rate flowing into the outdoor heat exchanger 160 isreduced and the outside air volume flowing into the outside air passage70 a is reduced with respect to the normal heating operation.

In addition, the air conditioning control apparatus switches thethree-direction valve 42 of the coolant circulation circuit 40 into thecoolant circuit which allows the coolant to flow into the radiator 43 asindicated by broken line arrows in FIG. 12. Accordingly, the refrigerantdoes not circulate in the heat pump cycle 10, and the coolantcirculation circuit 40 is switched to the coolant circuit in which therefrigerant flows as indicated by broken line arrows in FIG. 12.

Therefore, the heat of the coolant flowing in the coolant tubes 43 a ofthe radiator 43 is transferred to the outdoor heat exchanger 160 via theouter fins 70 b, and defrosting of the outdoor heat exchanger 160 isperformed. In other words, defrosting which utilizes waste heat of thetraveling electric motor MG effectively is achieved.

(c) Cooling Operation

The cooling operation starts when the cooling operation mode is selectedby a select switch in a state in which the operation switch of theoperation panel turns on. At the time of the cooling operation, the airconditioning control apparatus opens the opening-and-closing valve 15 a,and switches the three-direction valve 15 b to the refrigerant flowchannel that connects the outlet side of the outdoor heat exchanger 160and the inlet side of the cooling fixed throttle 19. Accordingly, theheat pump cycle 10 is switched to the refrigerant flow channel in whichthe refrigerant flows as indicated by the solid line arrows in FIG. 13.

At this time, the three-direction valve 42 of the coolant circulationcircuit 40 is switched to the coolant circuit which allows the coolantto flow into the radiator 43 when a coolant temperature Tw is increasedto a reference temperature or higher, and is switched to the coolantcircuit which allows the coolant to flow while bypassing the radiator 43when the coolant temperature Tw is lowered to a temperature below thepredetermined reference temperature. In FIG. 13, a flow of the coolantwhen the coolant temperature Tw is increased to the referencetemperature or higher is indicated by broken line arrows.

In the heat pump cycle 10 at the time of the cooling operation, thehigh-pressure refrigerant discharged from the compressor 11 flows intothe indoor condenser 120 and exchanges heat with the air that has beenblown by the blower 32 and passed through the indoor evaporator 20 tothe vehicle interior, thereby the refrigerant radiating heat. Thehigh-pressure refrigerant flowed out form the indoor condenser 120 flowsinto the outdoor heat exchanger 160 via the fixed throttle bypassingpassage 140 since the opening-and-closing valve 15 a is opened. Thelow-pressure refrigerant flowing into the outdoor heat exchanger 160further radiates heat to the outside air blown by the blower fan 17.

The refrigerant flowing out from the outdoor heat exchanger 160 isdecompressed and expanded by the cooling fixed throttle 19 since thethree-direction valve 15 b is switched to the refrigerant flow channelwhich connects the outlet side of the outdoor heat exchanger 160 and theinlet side of the cooling fixed throttle 19. The refrigerant flowing outfrom the cooling fixed throttle 19 flows into the indoor evaporator 20,and absorbs heat from the air blown by the blower 32 to the vehicleinterior, thereby the refrigerant evaporating. Accordingly, the airblown to the vehicle interior is cooled.

The refrigerant flowing out from the indoor evaporator 20 flows into theaccumulator 18 and is separated into gas and liquid. A gas-phaserefrigerant that has been separated by the accumulator 18 is absorbed bythe compressor 11, and again compressed. As described thus far, at thetime of the cooling operation, the air blown to the vehicle interior iscooled by the low-pressure refrigerant absorbing heat from the air blownto the vehicle interior and evaporating in the indoor evaporator 20, sothat the vehicle interior may be cooled.

In the vehicle air conditioning apparatus 1 of the present embodiment,various operations can be executed by switching the refrigerant flowchannel of the heat pump cycle 10 and the coolant circuit of the coolantcirculation circuit 40 as described above. Furthermore, in the presentembodiment, since the characteristic heat exchanger 70 described aboveis employed, the heat exchange amount among three types of fluids,namely, the refrigerant, the coolant, and the outside air may beadjusted adequately.

The heat exchanger 70 described in the second to the fourth embodimentsmay be applied to the heat pump cycle 10 of the present embodiment.

Sixth Embodiment

Subsequently, a sixth embodiment of the present disclosure will bedescribed with reference to FIG. 14 to FIG. 16. In the presentembodiment, an example in which configurations of a heat pump cycle 10and a coolant circulation circuit 40 of the fifth embodiment aremodified will be described. In FIG. 14 to FIG. 16, a flow of arefrigerant in the heat pump cycle 10 is indicated by a solid line, anda flow of a coolant in the coolant circulation circuit 40 is indicatedby broken line arrows.

Specifically, the coolant circulation circuit 40 of the presentembodiment is a coolant circulation circuit configured to circulate thecoolant as a cooling medium (heat medium) to the coolant flow channelformed in the interior of the engine EG, which is one of thevehicle-mounted devices associated with heat generation at the time ofoperation to cool an engine EG. In other words, in the presentembodiment, a traveling electric motor MG of the fifth embodiment iseliminated, and instead, the engine EG is arranged.

In addition, in the present embodiment, an indoor condenser 120 of thefifth embodiment is eliminated, and a composite-type heat exchanger 70of the fifth embodiment is arranged in a casing 31 of an indoor airconditioning unit 30. An outdoor heat exchanger 160 of the fifthembodiment in this heat exchanger 70 is functioned as the indoorcondenser 120.

The radiator 43 of the fifth embodiment in the heat exchanger 70 isfunctioned as a heat collection heat exchanger 45 for heating thecoolant by heat of the refrigerant. Accordingly, in the heat pump cycle10 of the present embodiment, a warm-up operation for warm-up the engineby heating the coolant by the heat of the refrigerant can be executed.The heat collection heat exchanger 45 is arranged in a bypass passage 44of the coolant circulation circuit 40.

In contrast, the outdoor heat exchanger 160 is configured as a singleheat exchanger configured to cause the refrigerant flowing in aninterior and an outside air blown from a blower fan 17 to exchange heatwith each other. In the same manner, the radiator 43 is configured as asingle heat exchanger configured to cause the coolant flowing in theinterior and the outside air blown from a blower fan 46 to exchange heatwith each other.

Other structures are the same as those of the fifth embodiment. In thepresent embodiment, although the warm-up operation is executed insteadof a defrosting operation, other operations are the same as those of thefifth embodiment.

Subsequently, the warm-up operation will be described. Here, in order torestrict an overheat of the engine EG, a temperature of the coolant ismaintained to be temperatures not higher than a predetermined upperlimit temperature, and in order to reduce a friction loss caused by anincrease in viscosity of lubricating oil sealed in the interior of theengine EG, the temperature of the coolant is preferably maintained to bea temperature not lower than a lower limit temperature.

Accordingly, in the heat pump cycle 10 of the present embodiment, thewarm-up operation is executed when a coolant temperature Tw is decreasedto a predetermined reference temperature or below at the time of theheating operation. In this warm-up operation, a three-direction valve 15b of the heat pump cycle 10 is operated in the same manner as the normalheating operation, and a three-direction valve 42 of the coolantcirculation circuit 40 is switched to a coolant circuit that causes thecoolant to flow while bypassing the radiator 43 as indicated by brokenline arrows in FIG. 15, that is, causes the coolant to flow into theheat collection heat exchanger 45.

Therefore, as illustrated by arrows of the solid line in FIG. 15, ahigh-pressure high-temperature refrigerant discharged from a compressor11 flows into the indoor condenser 120 in the same manner as in thenormal heating operation. A heat of the high-temperature high-pressurerefrigerant flowing into the indoor condenser 120 is transferred to anair blown by a blower 32 and is transferred to the coolant via outerfins 70 b since the circuit is switched to the coolant circuit whichallows the three-direction valve 42 to flow the coolant to the heatcollection heat exchanger 45. Other operations are the same as those atthe normal heating operation.

As described thus far, at the time of warm-up operation, an air blown toa vehicle interior is heated by the heat of the refrigerant dischargedfrom the compressor 11 by the indoor condenser 120, so that the vehicleinterior may be heated. The heat of the refrigerant discharged from thecompressor 11 in the indoor condenser 120 is also transferred to thecoolant via the outer fins 70 b, so that the temperature of the coolantincreases. Therefore, by using the heat of the refrigerant, the warm-upof the engine EG is achieved.

The heat exchanger 70 described in the second to the fourth embodimentsmay be applied to the heat pump cycle 10 of the present embodiment.

The present disclosure is not limited to the above-mentionedembodiments, and may have various modifications as described belowwithout departing from the gist of the present disclosure.

(1) In the above-described embodiments, an example in which a first coreportion 701 including refrigerant tubes 12 a is arranged on thedownstream side of a second core portion 702 including both therefrigerant tubes 12 a and the coolant tubes 43 a in the direction ofthe refrigerant flow in the heat exchanger 70 has been described.However, the plurality of first core portions may be provided.

For example, as illustrated in FIG. 17, a first core portion 703including the refrigerant tubes 12 a may be provided on the upstreamside of the second core portion 702 in the direction of the refrigerantflow (specifically, a path on the most upstream side in the direction ofthe refrigerant flow).

(2) In the embodiments described above, an example in which one each ofthe refrigerant tubes 12 a and the coolant tubes 43 a is arrangedalternately in the second core portion 702 of the upstream heatexchanging portion 71 has been described. However, the arrangement ofthe refrigerant tubes 12 a and the coolant tubes 43 a are not limitedthereto.

For example, in the second core portion 702 of the upstream heatexchanging portion 71, a coolant tubes 43 a may be arranged after everytwo of the refrigerant tubes 12 a. In other words, in the upstream heatexchanging portion 71, the two refrigerant tubes 12 a may be arrangedbetween the adjacent coolant tubes 43 a.

(3) In the first embodiment described above, an example in which therefrigerant of the heat pump cycle 10 is employed as a first fluid andthe coolant of the coolant circulation circuit 40 is employed as asecond fluid, and the outside air blown by the blower fan 17 is employedas a third fluid has been described. However, the first to the thirdfluid are not limited thereto. For example, in the same manner as thesixth embodiment, the air blown to the vehicle interior may be employedas the third fluid. The third fluid may also be a coolant.

For example, the first fluid may be a high-pressure side refrigerant ormay be a low-pressure side refrigerant of the heat pump cycle 10.

For example, a coolant for cooling electric device such as an inverterconfigured to supply power to the engine, the traveling electric motorMG may be employed as the second fluid. Oil for cooling may be employedas the second fluid to cause the second heat exchange portion tofunction as an oil cooler or a heat storage agent, a cooling storageagent or the like may be employed as the second fluid.

In addition, in the case where the heat pump cycle 10 to which the heatexchanger 70 of the present disclosure is applied is applied to astationary air conditioning apparatus, a cool temperature storage, or anautomatic vending machine, a coolant for cooling an engine, an electricmotor, and other electric devices as a drive source of the compressor ofthe heat pump cycle 10 may be employed as the second fluid.

In addition, in the above embodiment, an example in which the heatexchanger 70 of the present disclosure is applied to the heat pump cycle(the refrigeration cycle). However, the application of the heatexchanger 70 according to the present disclosure is not limited thereto.In other words, the heat exchanger 70 may be applied widely toapparatuses which perform heat exchange between three types of fluids.

For example, the heat exchanger 70 may be applied as a heat exchangerapplied to a vehicle cooling system. A configuration in which the firstfluid is a heat medium which has absorbed a heat of firstvehicle-mounted devices associated with heat generation at the time ofoperation, the second fluid is a heat medium which has absorbed a heatof a second vehicle-mounted device associated with heat generation atthe time of operation, and the third fluid is outdoor air is alsoapplicable.

More specifically, in the case of being applied to a hybrid vehicle, aconfiguration in which the first vehicle-mounted device is an engine EG,the first fluid is a coolant of the engine EG, the secondvehicle-mounted device is a traveling electric motor, and the secondfluid is a coolant of the traveling electric motor is also applicable.

Amounts of heat generation of these vehicle-mounted devices varyrespectively in accordance with a traveling state (traveling load) ofthe vehicle, so that the temperature of the coolant of the engine EG andthe temperature of the coolant of the traveling electric motor vary inaccordance with the traveling state of the vehicle as well. Therefore,according to this example, the heat generated by the vehicle-mounteddevices which generate a large amount of heat may be radiated not onlyto air, but also to vehicle-mounted devices which generate heat by asmall amount.

As the first vehicle-mounted device or the second vehicle-mounteddevice, an exhaust air reflux apparatus (EGR), a supercharger, a powersteering apparatus, a battery, and the like may be employed. The heatexchange portion may be functioned as an EGR cooler, an inter cooler, oran oil cooler for cooling power steering oil.

(4) In the embodiment described above, an example in which the electricthree-direction valve 42 is employed as circuit switching meansconfigured to switch the cooling medium circuit of the coolantcirculation circuit 40 has been described. However, the circuitswitching means is not limited thereto. For example, a thermostat valvemay be employed. The thermostat valve is a cooling medium temperaturereaction valve including a mechanic mechanism for opening and closing acooling medium path by displacing a valve body by a thermo wax(temperature sensing member) which is changed in volume in accordancewith the temperature. Therefore, by employing the thermostat valve, acoolant temperature sensor 52 may be eliminated.

(5) In the above embodiment, an example in which a normal fluorocarbonrefrigerant is used as the refrigerant has been described. However, thetype of the refrigerant is not limited thereto. A natural refrigerantsuch as carbon dioxide or a hydrocarbon system refrigerant may beemployed. Furthermore, the heat pump cycle 10 may constitute a part of asupercritical refrigeration cycle in which the discharged refrigerant ofthe compressor 11 has a critical pressure of the refrigerant or higher.

(6) In the fifth embodiment described above, an example in which theblown air is heated by causing the high-pressure refrigerant and theblown air to exchange heat in the indoor condenser 120 has beendescribed. However, instead of the indoor condenser 120, for example, aconfiguration in which a heat medium circulation circuit whichcirculates the heat medium is provided, and a water-refrigerant heatexchanger configured to exchange heat between the high-pressurerefrigerant and the heat medium and a heating heat exchanger configuredto heat the blown air by causing the heat medium heated by thewater-refrigerant exchanger and the blown air to exchange heat with eachother may be arranged in the heat medium circulation circuit is alsoapplicable.

In other words, a configuration in which the high-pressure refrigerantis used as a heat source, and the blown air is heated indirectly via theheat medium is also applicable. In addition, in the case of beingapplied to a vehicle having an internal combustion engine, the coolantof the internal combustion engine is used as the heat medium so as toflow through the heat medium circulation circuit. In an electricvehicle, a coolant for cooling the battery or the electric devices maybe flowed in the heat medium circulation circuit as the heat medium.

(7) In the second embodiment described above, an example in which afirst slit holes 70 c and a second slit holes 70 d are provided as aheat-shielding portion on the outer fins 70 b arranged between mostdownstream refrigerant tubes 121 a and the coolant tubes 43 a in thecase where the coolant tubes 43 a is provided in the first core portion701 has been described. However, the present disclosure is not limitedthereto, and the heat-shielding portion may not be provided.

In the case where the heat-shielding portion is not provided, the outerfins 70 b of the first core portion 701 includes a coolant side heatconnecting portions 72 b. However, since the number of the coolant sideheat connecting portions 72 b is smaller than the number of therefrigerant side heat connecting portions 71 b, the area used forradiating heat of the discharged refrigerant to the outside air in theouter fins 70 b arranged in the first core portion 701 becomes largerthan an area used for radiating the heat of the coolant to the outsideair. Therefore, the heat of the refrigerant flowing in the mostdownstream refrigerant tubes 121 a may be radiated sufficiently to theoutside air.

(8) In the second embodiment, an example in which the slit holes 70 c,70 d are employed as the heat-shielding portions has been described.However, the heat-shielding portion is not limited thereto. For example,the louvers may be formed instead of the slit holes 70 c, 70 d, or theouter fins 70 b may be cut.

Alternatively, the most downstream refrigerant tubes 121 a mayconstitute a part of the downstream heat exchanging portion 72, and therefrigerant tubes 12 a and the coolant tubes 43 a which constitute apart of the upstream heat exchanging portion 71 may be arrangedalternately in a stacked manner with each other.

What is claimed is:
 1. A heat exchanger including: a plurality of firsttubes in which a first fluid flows; a plurality of second tubes in whicha second fluid flows; a heat exchange portion including the plurality offirst tubes and the plurality of second tubes arranged in a stackedmanner and configured to radiate heats of the first fluid and the secondfluid to a third fluid; a third fluid channel in which the third fluidflows, the third fluid channel being provided in a periphery of theplurality of first tubes and the plurality of second tubes; and an outerfin arranged in the third fluid channel to promote a heat exchangebetween the first fluid and the third fluid and a heat exchange betweenthe second fluid and the third fluid, wherein the outer fin includesfirst heat connecting portions thermally connecting the plurality offirst tubes, and second heat connecting portions thermally connectingthe plurality of first tubes and the plurality of the second tubes, theplurality of first tubes is divided into a plurality of groups, theplurality of groups of the plurality of first tube are paths throughwhich the first fluids distributed from a same space flow in a samedirection, the plurality of first tubes include most downstream firsttubes which constitute a part of a final path that is a most downstreampath in a flowing direction of the first fluid, the heat exchangeportion includes a first core portion including the most downstreamfirst tubes, and the first heat connecting portions are larger in numberthan the second heat connecting portions in the first core portion. 2.The heat exchanger according to claim 1, wherein the first core portionincludes the most downstream first tubes and at least one of theplurality of second tubes, and the first core portion is provided with aheat-shielding portion located at a position corresponding to the secondheat connecting portion of the outer fin the heat-shielding portionlimiting heat transfer between the first fluid flowing in the mostdownstream first tubes and the second fluid flowing in the plurality ofsecond tubes.
 3. The heat exchanger according to claim 2, wherein theheat-shielding portion includes a slit hole penetrating through theouter fin.
 4. The heat exchanger according to claim 1, wherein the firstfluid is a refrigerant for a vapor compression refrigeration cycle, andthe heat exchange portion causes the refrigerant to concentrate.
 5. Theheat exchanger according to claim 1, wherein the plurality of firsttubes include second-most downstream first tubes that constitute a partof a path immediately before the final path in the flowing direction ofthe first fluid, and the second-most downstream first tubes, throughwhich the first fluid flows, and the plurality of second tubes, throughwhich the second fluid flows, are arranged adjacent to each other suchthat the first fluid and the second fluid are same in flowing direction.6. The heat exchanger according to claim 1, wherein the plurality offirst tubes and the plurality of second tubes are arranged alternatelyin a stacked manner except for the final path.
 7. The heat exchangeraccording to claim 1, wherein the heat exchange portion includes anupstream heat exchanging portion and a downstream heat exchangingportion arranged on a downstream side of the upstream heat exchangingportion in a flowing direction of the third fluid, the most downstreamfirst tubes constitute a part of the downstream heat exchanging portion,and the first tubes and the second tubes in the upstream heat exchangingportion are arranged alternately in a stacked manner.
 8. The heatexchanger according to claim 1, wherein the heat exchange portionfurther includes a second core portion having the plurality of secondtubes and the plurality of first tubes other than the most downstreamfirst tubes, and the plurality of first tubes and the plurality ofsecond tubes in the second core portion are arranged alternately in astacked manner.
 9. The heat exchanger according to claim 1, furthercomprising a dummy tube in which both the first fluid and the secondfluid do not flow, the dummy tube being arranged between the mostdownstream first tubes and the plurality of second tubes.
 10. The heatexchanger according to claim 1, wherein the plurality of first tubesinclude second-most downstream first tubes which constitute a part of apath immediately before the final path in the flowing direction of thefirst fluid, and a flow-channel total sectional area of the mostdownstream first tubes constituting the part of the final path issmaller than a flow-channel total sectional area of the second-mostdownstream first tubes.
 11. The heat exchanger according to claim 1,wherein the heat exchange portion includes an upstream heat exchangingportion and a downstream heat exchanging portion arranged on thedownstream side of the upstream heat exchanging portion in the flowingdirection of the third fluid, the upstream heat exchanging portionincludes a part of the most downstream first tubes of the first coreportion, the downstream heat exchanging portion includes a part of themost downstream first tubes of the first core portion), and the part ofthe most downstream first tubes of the downstream heat exchangingportion is connected to the part of the most downstream first tubes ofthe upstream heat exchanging portion such that the first fluid flowsfrom the downstream heat exchanging portion to the upstream heatexchanging portion in the most downstream first tubes.
 12. The heatexchanger according to claim 1, wherein the number of the second heatconnecting portion is zero in the first core portion, and the first coreportion includes only the most downstream first tubes.